Question

giúp mình nhé . Tìm x

a, 2x²⁺3(x-1)(x+1) = 5x (x+1)

3x+5 = 2 (x-1) +x

(x+2) (x-2)-(x-2)(x-2)=8x

 

Answer 1

a) \(2x^2+3\left(x-1\right)\left(x+1\right)=5x\left(x+1\right)\)

<=> \(2x^2+3\left(x^2-1\right)=5x^2+5x\)

<=>\(2x^2+3x^2-3-5x^2-5x=0\)

<=>\(-5x-3=0\)

<=>\(-5x=3\)

<=> \(x=\frac{-3}{5}\)

b) \(3x+5=2\left(x-1\right)+x\)

<=> \(3x+5-2x+2-x=0\)

<=>\(x+7=0\)

<=> \(x=-7\)

c)\(_{\left(x-2\right)\left(x+2\right)-\left(x-2\right)\left(x-2\right)=8x}\)

<=>\(\left(x^2-4\right)-\left(x-2\right)^2-8x=0\)

<=>\(\left(x^2-4\right)-\left(x^2-4x+4\right)-8x=0\)

<=>\(x^2-4-x^2+4x-4-8x=0\)

<=>\(-4x-8=0\)

<=>\(-4x=8\)

<=>\(x=-2\)

Đúng thì bình chọn cho mình nha