Question

2) Tìm \(x\), biết:

a) \(4\left(x+2\right)-7\left(2x-1\right)+9\left(3x-4\right)=30\)

b) \(2\left(5x-8\right)-3\left(4x-5\right)=4\left(3x-4\right)+11\)

c) \(5x\left(1-2x\right)-3x\left(x+18\right)=0\)

d) \(5x-3\left\{4x-2\left[4x-3\left(5x-2\right)\right]\right\}=182\)

e) \(5\left(3x+5\right)-4\left(2x-3\right)=5x+3\left(2x+12\right)+1\)

Answer 1

`a) 4(x+2)-7(2x-1)+9(3x-4)=30`

`4x+8-14x+1+27x-36=30`

`4x+8-14x+1+27x-36-30=0`

`17x-57=0`

`17x=57`

`x=57/17`

`-----------`

`b) 2(5x-8)-3(4x-5)=4(3x-4)+11`

`10x-16-12x+15=12x-16+11`

`10x-16-12x+15-12x+16-11=0`

`-14x-23=0`

`-14x=23`

`x=-23/14`

`------------`

`c)5x(1-2x)-3x(x+18)=0`

`5x-10x^2 -3x^2 -54x=0`

`-13x^2 -49x=0`

`x(-13x-49)=0`

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\13x+49\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{-49}{13}\end{matrix}\right.\)

`=>` Vậy `S={0;(-49)/13}`

`-------------`

`@` Mấy câu kia làm tương tự ;-;