K
Khách
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Các câu hỏi dưới đây có thể giống với câu hỏi trên
HQ
Hà Quang Minh
Giáo viên
19 tháng 9 2023
\(\begin{array}{l}a)A = 3x - 4{x^4} + {x^3}\\ = - 4{x^4} + {x^3} + 3x\\b)B = - 2{x^3} - 5{x^2} + 2{x^3} + 4x + {x^2} - 5\\ = ( - 2{x^3} + 2{x^3}) + \left( { - 5{x^2} + {x^2}} \right) + 4x - 5\\ = 0 + ( - 4{x^2}) + 4x - 5\\ = - 4{x^2} + 4x - 5\\c)C = {x^5} - \dfrac{1}{2}{x^3} + \dfrac{3}{4}x - {x^5} + 6{x^2} - 2\\ = \left( {{x^5} - {x^5}} \right) - \dfrac{1}{2}{x^3} + 6{x^2} + \dfrac{3}{4}x - 2\\ = - \dfrac{1}{2}{x^3} + 6{x^2} + \dfrac{3}{4}x - 2\end{array}\)
LN
3
28 tháng 6 2023
`@` `\text {Ans}`
`\downarrow`
`a,`
`2/5 + x = 2/7`
`=> x = 2/7 -2/5`
`=> x= - 4/35`
Vậy, `x=-4/35`
`b,`
`x + 3/5 = -2/5`
`=> x = -2/5 - 3/5`
`=> x=-1`
Vậy, `x=-1`
`c, `
`x - 8/5 = 3/7`
`=> x=3/7 + 8/5`
`=> x=71/35`
Vậy, `x=71/35`
`d,`
`3/5 - x = 7/3`
`=> x=3/5 - 7/3`
`=> x=-26/15`
Vậy, `x=-26/15`
H9
HT.Phong (9A5)
CTVHS
28 tháng 6 2023
a) \(\dfrac{2}{5}+x=\dfrac{2}{7}\)
\(\Rightarrow x=\dfrac{2}{7}-\dfrac{2}{5}\)
\(\Rightarrow x=-\dfrac{4}{35}\)
b) \(x+\dfrac{3}{5}=-\dfrac{2}{5}\)
\(\Rightarrow x=-\dfrac{2}{5}-\dfrac{3}{5}\)
\(\Rightarrow x=-1\)
c) \(x-\dfrac{8}{5}=\dfrac{3}{7}\)
\(\Rightarrow x=\dfrac{3}{7}+\dfrac{8}{5}\)
\(\Rightarrow x=\dfrac{71}{35}\)
d) \(\dfrac{3}{5}-x=\dfrac{7}{3}\)
\(\Rightarrow x=\dfrac{3}{5}-\dfrac{7}{3}\)
\(\Rightarrow x=-\dfrac{26}{15}\)
H9
HT.Phong (9A5)
CTVHS
14 tháng 4 2023
Bài 1:
a) \(-5\left(x^2-3x+1\right)+x\left(1+5x\right)=x-2\)
\(\Rightarrow-5x^2+15x-5+x+5x^2=x-2\)
\(\Rightarrow16x-5=x-2\)
\(\Rightarrow16x-x=5-2\)
\(\Rightarrow15x=3\)
\(\Rightarrow x=\dfrac{15}{3}=5\)
b) \(12x^2-4x\left(3x+5\right)=10x-17\)
\(\Rightarrow12x^2-12x^2-20x=10x-17\)
\(\Rightarrow-20x=10x-17\)
\(\Rightarrow-20x-10x=-17\)
\(\Rightarrow-30x=-17\)
\(\Rightarrow x=\dfrac{-30}{-17}=\dfrac{30}{17}\)
c) \(-4x\left(x-5\right)+7x\left(x-4\right)-3x^2=12\)
\(\Rightarrow-4x^2+20x+7x^2-28x-3x^2=12\)
\(\Rightarrow-8x=12\)
\(\Rightarrow x=\dfrac{12}{-8}=-\dfrac{4}{3}\)
Bài 2:
a) \(\left(x+5\right)\left(x-7\right)-7x\left(x-3\right)\)
\(=x^2-7x+5x-35-7x^2+21x\)
\(=-6x^2+19x-35\)
b) \(x\left(x^2-x-2\right)-\left(x-5\right)\left(x+1\right)\)
\(=x^3-x^2-2x-x^2+x-5x-5\)
\(=x^3-2x^2-6x-5\)
c) \(\left(x-5\right)\left(x-7\right)-\left(x+4\right)\left(x-3\right)\)
\(=x^2-7x-5x+35-x^2-3x+4x-12\)
\(=11x+23\)
d) \(\left(x-1\right)\left(x-2\right)-\left(x+5\right)\left(x+2\right)\)
\(=x^2-2x-x+2-x^2+2x+5x+10\)
\(=4x+12\)
NN
Nguyễn Ngọc Anh Minh
CTVHS
VIP
20 tháng 7 2023
Bài 2:
\(\dfrac{a+b}{a-b}=\dfrac{c+a}{c-a}\)
\(\Rightarrow\dfrac{a+b}{c+a}=\dfrac{a-b}{c-a}=\dfrac{a+b+a-b}{c+a+c-a}=\dfrac{a}{c}\) (T/c dãy tỷ số = nhau)
\(\Rightarrow\dfrac{a+b}{c+a}=\dfrac{a}{c}\Rightarrow c\left(a+b\right)=a\left(c+a\right)\)
\(\Rightarrow ac+bc=ac+a^2\Rightarrow a^2=bc\)
HN
28 tháng 8 2021
a,
\(5^{x+4}-3.5^{x+3}=2.5^{11}\)
\(\Rightarrow5^{x+3}\left(5-3\right)=2.5^{11}\)
\(\Rightarrow5^{x+3}2=2.5^{11}\)
\(\Rightarrow5^{x+3}=5^{11}\)
\(\Rightarrow x+3=11\)
\(\Rightarrow x=8\)
HN
28 tháng 8 2021
b, (Check lai xem de sai o dau khong nhe)
\(3.5^{x+2}+4.5^{x+3}=19.5^{10}\)
Dat 5x ra ben ngoai
\(\Rightarrow5^x.5^23+5^x:5^{-3}.4\)
\(\Rightarrow5^x\left(5^2.3+5^{-3}.4\right)\)
\(\Rightarrow5^x\left(5^{-3}.5^5.3+5^{-3}.4\right)\)
\(\Rightarrow5^x[5^{-3}\left(5^53+4\right)\)
\(\Rightarrow5^x[5^{-3}\left(3125.3+4\right)\)
\(\Rightarrow5^x\left(5^{-3}\right).9379\)
=> Khong tim duoc gia tri cua x \(\Rightarrow x\in\varnothing\)
NN
1
21 tháng 12 2015
\(\frac{x-2}{\left(a+3\right)\left(5-a\right)}=\frac{1}{2\left(a+3\right)}+\frac{1}{2\left(5-a\right)}\)
\(\Rightarrow\frac{2\left(x-2\right)}{2\left(a+3\right)\left(5-a\right)}=\frac{5-a+a+3}{2\left(a+3\right)\left(5-a\right)}\)
\(\Rightarrow\) 2x - 4 = 8
\(\Rightarrow\) 2x = 12
\(\Rightarrow\) x = 6
NL
1
H9
HT.Phong (9A5)
CTVHS
3 tháng 9 2023
a) \(\dfrac{2}{3}\left(x+1\right)-\dfrac{4}{5}\left(x+2\right)=\dfrac{35}{2}\)
\(\Rightarrow\dfrac{2}{3}x+\dfrac{2}{3}-\dfrac{4}{5}x-\dfrac{8}{5}=\dfrac{35}{2}\)
\(\Rightarrow\left(\dfrac{2}{3}-\dfrac{4}{5}\right)x+\left(\dfrac{2}{3}-\dfrac{8}{5}\right)=\dfrac{35}{2}\)
\(\Rightarrow-\dfrac{2}{15}x-\dfrac{14}{15}=\dfrac{35}{2}\)
\(\Rightarrow-\dfrac{2}{15}x=\dfrac{553}{30}\)
\(\Rightarrow x=\dfrac{553}{30}:-\dfrac{2}{15}\)
\(\Rightarrow x=-\dfrac{553}{4}\)
b) \(4\left(x-2\right)+5\left(x+1\right)=-15\)
\(\Rightarrow4x-8+5x+5=-15\)
\(\Rightarrow\left(4+5\right)x+\left(-8+5\right)=-15\)
\(\Rightarrow9x-3=-15\)
\(\Rightarrow9x=-15+3\)
\(\Rightarrow x=\dfrac{-12}{9}\)
\(\Rightarrow x=-\dfrac{4}{3}\)
c) \(\dfrac{3}{2}:x+\left(-\dfrac{5}{2}\right)=-\dfrac{7}{3}\)
\(\Rightarrow\dfrac{3}{2}:x=-\dfrac{7}{3}+\dfrac{5}{2}\)
\(\Rightarrow\dfrac{3}{2}x=\dfrac{1}{6}\)
\(\Rightarrow x=\dfrac{1}{6}:\dfrac{3}{2}\)
\(\Rightarrow x=\dfrac{1}{9}\)