1-2+1-2=
A ko
B 5
C-9
K
Khách
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Những câu hỏi liên quan
6 tháng 3 2023
a: \(=\dfrac{x+1-4}{x+1}\cdot\dfrac{9-x^2+2x^2+2x-8}{-\left(x-3\right)\left(x+3\right)}\)
\(=\dfrac{x-3}{-\left(x-3\right)\left(x+3\right)}\cdot\dfrac{x^2+2x+1}{x+1}\)
\(=\dfrac{-x-1}{x+3}\)
b: Khi x=-5 thì \(M=\dfrac{-5-1}{-5+3}=\dfrac{-6}{-2}=3\)
c: Để M nguyên thì -x-1 chia hết cho x+3
=>-x-3+2 chia hết cho x+3
=>\(x+3\in\left\{1;-1;2;-2\right\}\)
=>\(x\in\left\{-2;-4;-5\right\}\)
HY
2
24 tháng 1
a: \(\dfrac{11}{4}+\left(-\dfrac{3}{5}+\dfrac{1}{3}\right):\dfrac{-4}{9}\)
\(=\dfrac{11}{4}+\dfrac{-9+5}{15}\cdot\dfrac{9}{-4}\)
\(=\dfrac{11}{4}+\dfrac{-4}{15}\cdot\dfrac{9}{-4}\)
\(=\dfrac{11}{4}+\dfrac{3}{5}=\dfrac{55+12}{20}=\dfrac{67}{20}\)
b: \(\dfrac{2}{6}-\left(-\dfrac{3}{3}+\dfrac{4}{7}\right):\dfrac{-9}{5}\)
\(=\dfrac{2}{6}-\left(-1+\dfrac{4}{7}\right)\cdot\dfrac{-5}{9}\)
\(=\dfrac{2}{6}-\dfrac{-3}{7}\cdot\dfrac{-5}{9}\)
\(=\dfrac{1}{3}-\dfrac{15}{63}\)
\(=\dfrac{6}{63}=\dfrac{2}{21}\)
c: \(21-\dfrac{15}{4}:\left(\dfrac{3}{8}-\dfrac{1}{6}\right)\)
\(=21-\dfrac{15}{4}:\dfrac{3\cdot3-4}{24}\)
\(=21-\dfrac{15}{4}\cdot\dfrac{24}{5}\)
\(=21-3\cdot6=3\)
MP
24 tháng 1
\(a.\dfrac{11}{4}+\left(-\dfrac{3}{5}+\dfrac{1}{3}\right):-\dfrac{4}{9}\)
\(=\dfrac{11}{4}+\left(-\dfrac{4}{15}\right):-\dfrac{4}{9}\)
\(=\dfrac{11}{4}+\dfrac{3}{5}=\dfrac{67}{20}\)
\(b.\dfrac{2}{6}-\left(-\dfrac{3}{3}+\dfrac{4}{7}\right):-\dfrac{9}{5}\)
\(=\dfrac{2}{6}-\left(-\dfrac{3}{7}\right):-\dfrac{9}{5}\)
\(=\dfrac{2}{6}-\dfrac{5}{21}=\dfrac{2}{21}\)
\(c.21-\dfrac{15}{4}:\left(\dfrac{3}{8}-\dfrac{1}{6}\right)\)
\(=21-\dfrac{15}{4}:\dfrac{5}{24}\)
\(=21-18=3\)
C
25 tháng 12 2022
\(-\dfrac{7}{2}-\left(\dfrac{5}{3}\right)^2:\dfrac{10}{27}\\ =-\dfrac{7}{2}-\dfrac{25}{9}:\dfrac{10}{27}\\ =-\dfrac{7}{2}-\dfrac{25}{9}.\dfrac{27}{10}\\ =-\dfrac{7}{2}-\dfrac{675}{90}\\ =-\dfrac{7}{2}-\dfrac{75}{9}\\ =-\dfrac{63}{18}-\dfrac{150}{18}\\ =-\dfrac{213}{18}\)
`a) -3/5 xx 7/9 + (-3/5) xx 2/9 + 3/5`
`=-3/5 xx (7/9+2/9) + 3/5`
`=-3/5 xx 1 + 3/5`
`=-3/5+3/5`
`=0`
31 tháng 10 2021
\(1,\\ a,3^{2^3}=3^8>3^6=\left(3^2\right)^3\\ b,\left(-8\right)^9=\left(-2\right)^{27}< \left(-2\right)^{25}=\left(-32\right)^5\\ c,2^{21}=8^7< 9^7=3^{14}\\ 2,\)
\(a,\) Áp dụng tcdtsbn:
\(\dfrac{a}{b}=\dfrac{c}{d}\Leftrightarrow\dfrac{a}{c}=\dfrac{b}{d}=\dfrac{5a+3b}{5c+3d}=\dfrac{5a-3b}{5c-3d}\)
\(b,\) Sửa: \(\dfrac{ab}{cd}=\dfrac{\left(a+b\right)^2}{\left(c+d\right)^2}\)
Đặt \(\dfrac{a}{b}=\dfrac{c}{d}=k\Leftrightarrow a=bk;c=dk\)
\(\Leftrightarrow\dfrac{ab}{cd}=\dfrac{b^2k}{d^2k}=\dfrac{b^2}{d^2};\dfrac{\left(a+b\right)^2}{\left(c+d\right)^2}=\dfrac{\left[b\left(k+1\right)\right]^2}{\left[d\left(k+1\right)\right]^2}=\dfrac{b^2}{d^2}\\ \LeftrightarrowĐpcm\)
NT
2
KH
0
DB
2
PH
9 tháng 2 2020
1) 3a-b-2c=2 với b=6;c=-1
thay b=6;c=-1 vào bt ta có:
3a - 6- 2(-1)=2
3a-6 -(-2)=2
3a-6= 2+(-2)
3a-6=0
3a=0+6
3a=6
a=6:3
a=2
2) 12-a+b+5c=-1 với b=-7;c=5
thay b=-7;c=5 vào bt ta có :
12-a + (-7) + 5.5=-1
12-a +(-7) +25=-1
12-a + (-7) = -1-25
12-a +(-7) = -26
12-a = -26-(-7)
12-a=-19
a=12-(-19)
a=31
3) 1-2b+c-3a=-9 với b=-3;c=-7
thay b=-3;c=-7 vào bt ta có:
1- 2(-3) + (-7) -3a=-9
1-(-6) +(-7) -3a=-9
7 + (-7) -3a =-9
0-3a =-9
3a=0-(-9)
3a=9
a=9:3
a=3
MH
25 tháng 11 2021
\(2x^3+x^2-4x-12\)
\(=2x^3+5x^2+6x-4x^2-10x-12\)
\(=\left(2x^3+5x^2+6x\right)-\left(4x^2+10x+12\right)\)
\(=x\left(2x^2+5x+6\right)-2\left(2x^2+5x+6\right)\)
\(=\left(x-2\right)\left(2x^2+5x+6\right)\)
25 tháng 11 2021
\(a,2x^3+x^2-4x-12=\left(2x^3-4x^2\right)+\left(5x^2-10x\right)+\left(6x-12\right)=2x^2\left(x-2\right)+5x\left(x-2\right)+6\left(x-2\right)=\left(x-2\right)\left(2x^2+5x+6\right)\)
\(b,x^5-xy^4+x^4y-y^5=x\left(x^4-y^4\right)+y\left(x^4-y^4\right)=\left(x+y\right)\left(x^4-y^4\right)=\left(x+y\right)\left(x^2-y^2\right)\left(x^2+y^2\right)=\left(x+y\right)^2\left(x-y\right)\left(x^2+y^2\right)\)
\(c,\left(x+1\right)\left(x+3\right)\left(x+5\right)\left(x+7\right)-9=\left[\left(x+1\right)\left(x+7\right)\right]\left[\left(x+3\right)\left(x+5\right)\right]-9=\left(x^2+8x+7\right)\left(x^2+8x+15\right)-9\)
đặt \(x^2+8x+11=y\)
\(\left(x^2+8x+7\right)\left(x^2+8x+15\right)-9=\left(y-4\right)\left(y+4\right)-9=y^2-16-9=y^2-25=\left(y-5\right)\left(y+5\right)=\left(x^2+8x+11-5\right)\left(x^2+8x+11+5\right)=\left(x^2+8x+6\right)\left(x^2+8x+16\right)=\left(x^2+8x+6\right)\left(x+4\right)^2\)
= -2 nha bn
HT
1-2+1-2=-2 nha bạn