Question

tìm x, biết

a. 4x(x - 5) - (x - 1) (4x -3) = 5

b. ( x - 5) (x - 1) = (x - 1) (x - 2)

c. (x - 5) (-x + 4) - (x -1) (x  -  1) (x + 3) = -2x²

d. (x + 1) (x² - x  + 1) - x (x² - 3) = 4

Answer 1

a) \(4x\left(x-5\right)-\left(x-1\right)\left(4x-3\right)=5\)

\(\Leftrightarrow4x^2-20x-4x^2+7x-3=5\)

\(\Leftrightarrow-13x-3=5\)

\(\Leftrightarrow x=\frac{-8}{13}\)

Answer 2

b) \(\left(x-5\right)\left(x-1\right)=\left(x-1\right)\left(x-2\right)\)

\(\Leftrightarrow x^2-6x+5=x^2-3x+2\)

\(\Leftrightarrow-3x+3=0\)

\(\Leftrightarrow x=1\)

Vậy x=1