thực hiện pháp tính sau:a) (x3 8y3):(2y x) b.$\frac{a-1}{2\left(a-4\right)} \frac{a}{a-4}$ c. (x3 3x2y 3xy2 y3):(2x 2y)d. (x-5)2 (7-x)(x 2) e.$\frac{3x}{x-2}-\frac{2x 1}{2-x}$ ...

thực hiện phép tính a) (x3+8y3):(2y+x) b.$\frac{a-1}{2\left(a-4\right)}+\frac{a}{a-4}$ c. (x3+3x2y+3xy2+y3):(2x+2y) d. (x-5)2+(7-x)(x+2) e.$\frac{3x}{x-2}-\frac{2x+1}{2-x}$ f. $\left(\frac{x+2}{x+1}-\frac{2x}{x-1}\right)\cdot\frac{3x+3}{x}+\frac{4x^2+x+7}{x^2-x}$ g.$\left(\frac{1}{x+1}-\frac{3}{x^{3^{ }}+1}+\frac{3}{x^2-x+1}\right)\cdot\left(\frac{3x^2-3x+3}{\left(x+1\right)\left(x+2\right)}\right)$ h.$\frac{1}{3x-2}-\frac{1}{3x+2}-\frac{3x+6}{4-9x^2}$ Nguyễn Nam giúp...

0

LL

Lyly Luta

26 tháng 11 2017

1

NN

Nguyễn Nam

26 tháng 11 2017

) $\dfrac{x^3+8y^3}{2y+x}$

$=\dfrac{x^3+\left(2y\right)^3}{x+2y}$

$=\dfrac{\left(x+2y\right)\left[x^2+x.2y+\left(2y\right)^2\right]}{x+2y}$

$=x^2+2xy+4y^2$

b) $\dfrac{a-1}{2\left(a-4\right)}+\dfrac{a}{a-4}$ MTC: $2\left(a-4\right)$

$=\dfrac{a-1}{2\left(a-4\right)}+\dfrac{2a}{2\left(a-4\right)}$

$=\dfrac{a-1+2a}{2\left(a-4\right)}$

$=\dfrac{3a-1}{2\left(a-4\right)}$

c) $\dfrac{x^3+3x^2y+3xy^2+y^3}{2x+2y}$

$=\dfrac{\left(x+y\right)^3}{2\left(x+y\right)}$

$=\dfrac{\left(x+y\right)^2}{2}$

d) $\left(x-5\right)^2+\left(7-x\right)\left(x+2\right)$

$=\left(x^2-2.x.5+5^2\right)+\left(7x+14-x^2-2x\right)$

$=x^2-10x+25+7x+14-x^2-2x$

$=39-5x$

e) $\dfrac{3x}{x-2}-\dfrac{2x+1}{2-x}$

$=\dfrac{3x}{x-2}+\dfrac{2x+1}{x-2}$

$=\dfrac{3x+2x+1}{x-2}$

$=\dfrac{5x+1}{x-2}$

h) $\dfrac{1}{3x-2}-\dfrac{1}{3x+2}-\dfrac{3x+6}{4-9x^2}$

$=\dfrac{1}{3x-2}-\dfrac{1}{3x+2}+\dfrac{3x+6}{9x^2-4}$

$=\dfrac{1}{3x-2}-\dfrac{1}{3x+2}+\dfrac{3x+6}{\left(3x-2\right)\left(3x+2\right)}$ MTC: $\left(3x-2\right)\left(3x+2\right)$

$=\dfrac{3x+2}{\left(3x-2\right)\left(3x+2\right)}-\dfrac{3x-2}{\left(3x-2\right)\left(3x+2\right)}+\dfrac{3x+6}{\left(3x-2\right)\left(3x+2\right)}$

$=\dfrac{\left(3x+2\right)-\left(3x-2\right)+\left(3x+6\right)}{\left(3x-2\right)\left(3x+2\right)}$

$=\dfrac{3x+2-3x+2+3x+6}{\left(3x-2\right)\left(3x+2\right)}$

$=\dfrac{3x+10}{\left(3x-2\right)\left(3x+2\right)}$

LL

Lyly Luta

27 tháng 11 2017

câu f ,g đâu

BT

bùi thị phương uyên

16 tháng 12 2019

1, Thực hiện tính cộng, trừ, nhân, chia các phân thức sau:

a,$\frac{2x-7}{10x-4}-\frac{3x+5}{4-10x}$

b,$\frac{2x+3}{4x^2y^2}:\frac{6x+9}{10x^2y}$

c,$\frac{x^2-y^2}{6x^2y^2}:\frac{x+y}{3xy}$

d,$\left(\frac{3x}{1-3x}+\frac{2x}{3x+1}\right):\frac{6x^2+10x}{1-6x+9x^2}$

1

𝑮𝒊𝒂 𝑯𝒖𝒚

17 tháng 12 2019

a) $\frac{2x-7}{10x-4}-\frac{3x+5}{4-10x}$

$=\frac{2x-7}{10x-4}-\frac{-\left(3x+5\right)}{-\left(4-10x\right)}$

$=\frac{2x-7}{10x-4}-\frac{5-3x}{10x-4}$

$=\frac{2x-7-\left(5-3x\right)}{10x-4}$

$=\frac{2x-7-5+3x}{10x-4}$

$=\frac{5x-12}{10x-4}$

NN

nguyen ngoc son

15 tháng 7 2020

thực hiện phép...

#Toán lớp 7

1

NL

Nguyễn Lê Phước Thịnh

15 tháng 7 2020

a) Ta có: $-2xy^2\cdot\left(x^3y-2x^2y^2+5xy^3\right)$

$=-2x^4y^3+4x^3y^4-10x^2y^5$

b) Ta có: $\left(-2x\right)\cdot\left(x^3-3x^2-x+1\right)$

$=-2x^4+6x^3+2x^2-2x$

c) Ta có: $3x^2\left(2x^3-x+5\right)$

$=6x^5-3x^3+15x^2$

d) Ta có: $\left(-10x^3+\frac{2}{5}y-\frac{1}{3}z\right)\cdot\left(-\frac{1}{2}xy\right)$

$=5x^4y-\frac{1}{5}xy^2+\frac{1}{6}xyz$

e) Ta có: $\left(3x^2y-6xy+9x\right)\cdot\left(-\frac{4}{3}xy\right)$

$=-4x^3y^2+8x^2y^2-12x^2y$

f) Ta có: $\left(4xy+3y-5x\right)\cdot x^2y$

$=4x^3y^2+3x^2y^2-5x^3y$

1.Với giá trị nào của biến thì giá trị của biểu thức bằng 0$\frac{x+1}{7};\frac{3x+3}{5};\frac{3x\left(x-5\right)}{x-7};\frac{2x\left(x+1\right)}{3x+4}$2.Tính giá trị của các biểu thức sau:$A=\frac{a^2\left(a^2+b^2\right)\left(a^{\text{4}}+b^{\text{4 }}\right)\left(a^8+b^8\right)\left(a^2-3b\right)}{\left(a^{10}+b^{10}\right)}$tại a=6;b=12$B=3xy\left(x+y\right)+2x^3y+2x^2y^2+5$tại x+y=0$C=2x+2y+3xy\left(x+y\right)+5\left(x^3y^2+x^2y^3\right)+4$tại...

PT

Phác Trí Nghiên

9 tháng 1 2016

Bài 1 :Thực hiện phép tính a, $\frac{2x}{x^2+2xy}+\frac{y}{xy-2y^2}+\frac{4}{x^2-4y^2}$ b$\frac{1}{x-y}+\frac{3xy}{y^3-x^3}+\frac{x-y}{x^2+xy+y^2}$ c, $\frac{xy}{2x-y}-\frac{x^2-1}{y-2x}$ d,$\frac{2\left(x+y\right)\left(x-y\right)}{x}-\frac{-2y^2}{x}$ Bài 2: Thực hiện phép...

#Toán lớp 7

0

MT

mi tra

19 tháng 8 2020

1

NL

Nguyễn Lê Phước Thịnh

19 tháng 8 2020

Bài 1:

a) Ta có: $\frac{2x}{x^2+2xy}+\frac{y}{xy-2y^2}+\frac{4}{x^2-4y^2}$

$=\frac{2x}{x\left(x+2y\right)}+\frac{y}{y\left(x-2y\right)}+\frac{4}{\left(x-2y\right)\left(x+2y\right)}$

$=\frac{2}{x+2y}+\frac{y}{x-2y}+\frac{4}{\left(x-2y\right)\left(x+2y\right)}$

$=\frac{2\left(x-2y\right)}{\left(x+2y\right)\left(x-2y\right)}+\frac{y\left(x+2y\right)}{\left(x-2y\right)\left(x+2y\right)}+\frac{4}{\left(x-2y\right)\left(x+2y\right)}$

$=\frac{2x-4y+xy+2y^2+4}{\left(x-2y\right)\cdot\left(x+2y\right)}$

b) Ta có: $\frac{1}{x-y}+\frac{3xy}{y^3-x^3}+\frac{x-y}{x^2+xy+y^2}$

$=\frac{x^2+xy+y^2}{\left(x-y\right)\left(x^2+xy+y^2\right)}-\frac{3xy}{\left(x-y\right)\left(x^2+xy+y^2\right)}+\frac{\left(x-y\right)^2}{\left(x-y\right)\left(x^2+xy+y^2\right)}$

$=\frac{x^2+xy+y^2-3xy+x^2-2xy+y^2}{\left(x-y\right)\left(x^2+xy+y^2\right)}$

$=\frac{2x^2-4xy+2y^2}{\left(x-y\right)\left(x^2+xy+y^2\right)}$

$=\frac{2\left(x^2-2xy+y^2\right)}{\left(x-y\right)\left(x^2+xy+y^2\right)}$

$=\frac{2\left(x-y\right)^2}{\left(x-y\right)\left(x^2+xy+y^2\right)}$

$=\frac{2x-2y}{x^2+xy+y^2}$

c) Ta có: $\frac{xy}{2x-y}-\frac{x^2-1}{y-2x}$

$=\frac{xy}{2x-y}+\frac{x^2-1}{2x-y}$

$=\frac{x^2+xy-1}{2x-y}$

d) Ta có: $\frac{2\left(x+y\right)\left(x-y\right)}{x}-\frac{-2y^2}{x}$

$=\frac{2\left(x^2-y^2\right)+2y^2}{x}$

$=\frac{2x^2-2y^2+2y^2}{x}$

$=\frac{2x^2}{x}=2x$

Bài 2:

a) Ta có: $\frac{4x+1}{2}-\frac{3x+2}{3}$

$=\frac{3\left(4x+1\right)}{6}-\frac{2\left(3x+2\right)}{6}$

$=\frac{12x+3-6x-4}{6}$

$=\frac{6x-1}{6}$

b) Ta có: $\frac{x+3}{x}-\frac{x}{x-3}+\frac{9}{x^2-3x}$

$=\frac{\left(x+3\right)\left(x-3\right)}{x\left(x-3\right)}-\frac{x^2}{x\left(x-3\right)}+\frac{9}{x\left(x-3\right)}$

$=\frac{x^2-9-x^2+9}{x\left(x-3\right)}=\frac{0}{x\left(x-3\right)}=0$

c) Ta có: $\frac{x+3}{x^2+1}-\frac{1}{x^2+2}$

$=\frac{\left(x+3\right)\left(x^2+2\right)}{\left(x^2+1\right)\left(x^2+2\right)}-\frac{x^2+1}{\left(x^2+2\right)\left(x^2+1\right)}$

$=\frac{x^3+2x+3x^2+6-x^2-1}{\left(x^2+1\right)\left(x^2+2\right)}$

$=\frac{x^3+2x^2+2x+5}{\left(x^2+1\right)\left(x^2+2\right)}$

e) Ta có: $\frac{3}{2x^2+2x}+\frac{2x-1}{x^2-1}-\frac{2}{x}$

$=\frac{3}{2x\left(x+1\right)}+\frac{2x-1}{\left(x+1\right)\left(x-1\right)}-\frac{2}{x}$

$=\frac{3\left(x-1\right)}{2x\left(x+1\right)\left(x-1\right)}+\frac{2x\left(2x-1\right)}{2x\left(x+1\right)\left(x-1\right)}-\frac{2\cdot2\cdot\left(x+1\right)\left(x-1\right)}{2x\left(x+1\right)\left(x-1\right)}$

$=\frac{3x-3+4x^2-2x-4\left(x^2-1\right)}{2x\left(x+1\right)\left(x-1\right)}$

$=\frac{4x^2+x-3-4x^2+4}{2x\left(x+1\right)\left(x-1\right)}$

$=\frac{x+1}{2x\left(x+1\right)\left(x-1\right)}=\frac{1}{2x\left(x-1\right)}$

d) Ta có: $\frac{1}{3x-2}-\frac{4}{3x+2}-\frac{-10x+8}{9x^2-4}$

$=\frac{3x+2}{\left(3x-2\right)\left(3x+2\right)}-\frac{4\left(3x-2\right)}{\left(3x+2\right)\left(3x-2\right)}-\frac{-10x+8}{\left(3x-2\right)\left(3x+2\right)}$

$=\frac{3x+2-12x+8+10x-8}{\left(3x-2\right)\left(3x+2\right)}$

$=\frac{x+2}{\left(3x-2\right)\left(3x+2\right)}$

f) Ta có: $\frac{3x}{5x+5y}-\frac{x}{10x-10y}$

$=\frac{3x}{5\left(x+y\right)}-\frac{x}{10\left(x-y\right)}$

$=\frac{3x\cdot2\cdot\left(x-y\right)}{10\left(x+y\right)\left(x-y\right)}-\frac{x\cdot\left(x+y\right)}{10\left(x-y\right)\left(x+y\right)}$

$=\frac{6x^2-6xy-x^2-xy}{10\left(x-y\right)\left(x+y\right)}$

$=\frac{5x^2-7xy}{10\left(x-y\right)\left(x+y\right)}$

Bài 1: Thực hiện các phép tính...

HL

Hoàng Linh Nhi

11 tháng 8 2020

#Giáo dục công dân lớp 8

0

HL

Hoàng Linh Nhi

12 tháng 8 2020

Mình biết rồi, cảm ơn bạn

1. Thực hiện phép tínha) $\left(3x^2y-6xy+9x\right).\left(\frac{-4}{3xy}\right)$b) $\left(\frac{1}{3}x+2y\right).\left(\frac{1}{9}x^2-\frac{2}{3}xy+4y^2\right)$c) (x-2) ( $x^2-5x+1$) + x ( $x^2+11$)d) (x - 3y ) $\left(x^2+3xy+9y^2\right)$e) $\left(3+x\right)\left(x^2+3x-5\right)$f) (x+2)(x-2)-(2x+1)2. Rút gọn biểu thứca ) $\left(3x+2\right)^2+2\left(2+3x\right)\left(1-2y\right)+\left(2y-1\right)^2$b...

CN

Cấn Ngọc Minh

20 tháng 10 2020

Câu hỏi hay

2

NT

nguyen thi tra my

21 tháng 10 2020

cau a : (3x^2y-6xy+9x)(-4/3xy)

=-4/3xy.3x^2y+4/3xy.6xy-4/3xy.9x

=-4x+8-8y

cau b : (1/3x+2y)(1/9x^2-2/3xy+4y^2)

=(1/3)^3-2/9x^2y+8y^3+4/3xy^2+2/9x^2y-4/3xy^2+8y^3

=(1/3)^3 + (2y)^3x-2

cau c : (x-2)(x^2-5x+1)+x(x^2+11)

=x^3-5x^2+x-2x^2+10x-2+x^3+11x

=2x^3-7x^2+22x-2

cau d := x^3 + 6xy^2 -27y^3

cau e := x^3 + 3x^2 -5x - 3x^2y - 9xy = 15y

cau f := x^2-2x+2x -4-2x-1

= x(x-2)-5

NT

nguyen thi tra my

21 tháng 10 2020

cau e la + 15y ko phai =15y

Bài 1: rút gọn phân thứca) $\frac{14xy^2\left(2x-3y\right)}{21x^2y\left(2x-3y\right)^2}$b) $\frac{8xy\left(3x-1\right)^2}{12x^3\left(1-3x\right)}$c) $\frac{20x^2-45}{\left(2x+3\right)^2}$d) $\frac{5x^2-10xy}{2\left(2y-x\right)^3}$e) $\frac{80x^3-125x}{3\left(x-3\right)-\left(x-3\right)\left(8-4x\right)}$f) $\frac{9-\left(x+5\right)^2}{x^2+4x+4}$g) $\frac{32x-8x^2+2x^3}{x^3+64}$h) $\frac{5x^3+5x}{x^4-1}$Bài 2: Quy đồng mẫu thức của các phân thức...

K

KAl(SO4)2·12H2O

14 tháng 2 2020

1

AZ

Agatsuma Zenitsu

14 tháng 2 2020

Bài 2: $a,\frac{7x-1}{2x^2+6x}=\frac{7x-1}{2x\left(x+3\right)}=\frac{\left(7x-1\right)\left(x-3\right)}{2x\left(x+3\right)\left(x-3\right)}$

$\frac{5-3x}{x^2-9}=\frac{5-3x}{\left(x-3\right)\left(x+3\right)}=\frac{\left(5-3x\right)2x}{2x\left(x-3\right)\left(x+3\right)}$

$b,\frac{x+1}{x-x^2}=\frac{x+1}{x\left(1-x\right)}=-\frac{x+1}{x\left(x+1\right)}=-\frac{2\left(x-1\right)\left(x+1\right)}{2x\left(x-1\right)^2}$

$\frac{x+2}{2-4x+2x^2}=\frac{x+2}{2\left(x-1\right)^2}=\frac{2x\left(x+2\right)}{2x\left(x-1\right)^2}$

$c,\frac{4x^2-3x+5}{x^3-1}=\frac{4x^2-3x+5}{\left(x-1\right)\left(x^2+x+1\right)}$

$\frac{2x}{x^2+x+1}=\frac{2x\left(x-1\right)}{\left(x-1\right)\left(x^2+x+1\right)}$

$\frac{6}{x-1}=\frac{6\left(x^2+x+1\right)}{\left(x-1\right)\left(x^2+x+1\right)}$

$d,\frac{7}{5x}=\frac{7.2\left(2y-x\right)\left(2y+x\right)}{2.5x\left(2y-x\right)\left(2y+x\right)}$

$\frac{4}{x-2y}=-\frac{4}{2y-x}=-\frac{4.2.5x\left(2x+x\right)}{2.5x\left(2y-x\right)\left(2y+x\right)}$

$\frac{x-y}{8y^2-2x^2}=\frac{x-y}{2\left(4y^2-x^2\right)}=\frac{x-y}{2\left(2y-x\right)\left(2y+x\right)}=\frac{5x\left(x-y\right)}{2.5x.\left(2y-x\right)\left(2y+x\right)}$

Bài 1: Thực hiện phép tính a. $\frac{11x+10}{3x-3}+\frac{15x+13}{4-4x}$ b. $\frac{5x+3}{x^2-3x}+\frac{9-x}{9-3x}$ c. $\frac{4xy-1}{5x^2y}-\frac{2xy-1}{5x^2y}$ d. $\frac{x+8}{x^2-16}-\frac{2}{x^2+4x}$ e. $\frac{x^2-49}{2x+1}.\frac{3}{7-x}$ f. $\frac{3x^2-2x}{x^2-1}.\frac{1-x^4}{\left(2-3x\right)^3}$ g. $\frac{5xy}{2x-3}:\frac{15xy^3}{12-8x}$ h....

PT

Phạm Tú Uyên

12 tháng 8 2020

3

AH

Akai Haruma

Giáo viên

12 tháng 8 2020

f)

$\frac{3x^2-2x}{x^2-1}.\frac{1-x^4}{(2-3x)^3}$

$=\frac{2x-3x^2}{x^2-1}.\frac{x^4-1}{(2-3x)^3}=\frac{x(2-3x)(x^2-1)(x^2+1)}{(x^2-1)(2-3x)^3}$

$=\frac{x(x^2+1)}{(2-3x)^2}$
g)

$\frac{5xy}{2x-3}:\frac{15xy^3}{12-8x}=\frac{5xy}{2x-3}.\frac{12-8x}{15xy^3}$

$=\frac{5xy}{2x-3}.\frac{-4(2x-3)}{15xy^3}=\frac{-4}{3y^2}$

h)

$\frac{x^2+2x}{3x^2-6x+3}:\frac{2x+4}{5x-5}=\frac{x(x+2)}{3(x-1)^2}:\frac{2(x+2)}{5(x-1)}$

$=\frac{x(x+2)}{3(x-1)^2}.\frac{5(x-1)}{2(x+2)}$

$=\frac{5x}{6(x-1)}$

AH

Akai Haruma

Giáo viên

12 tháng 8 2020

d)

$\frac{x+8}{x^2-16}-\frac{2}{x^2+4x}=\frac{x+8}{(x-4)(x+4)}-\frac{2}{x(x+4)}$

$=\frac{x(x+8)}{x(x-4)(x+4)}-\frac{2(x-4)}{x(x+4)(x-4)}$

$=\frac{x^2+8x-2(x-4)}{x(x+4)(x-4)}=\frac{x^2+6x+8}{x(x+4)(x-4)}$

$=\frac{(x+2)(x+4)}{x(x+4)(x-4)}=\frac{x+2}{x(x-4)}$
e)

$\frac{x^2-49}{2x+1}.\frac{3}{7-x}=\frac{(x-7)(x+7)}{2x+1}.\frac{-3}{x-7}$

$=\frac{-3(x+7)}{2x+1}$