Question

Tìm x: a) 2x.(x-1)+x.(x-2)=3x²-1 b) (x-4)²=2.(x-4)

Answer 1

Lời giải:

a)

$2x(x-1)+x(x-2)=3x^2-1$

$\Leftrightarrow 2x^2-2x+x^2-2x=3x^2-1$

$\Leftrightarrow 3x^2-4x=3x^2-1$

$\Leftrightarrow 4x=1$

$\Leftrightarrow x=\frac{1}{4}$

b)

$(x-4)^2=2(x-4)$

$\Leftrightarrow (x-4)^2-2(x-4)=0$

$\Leftrightarrow (x-4)(x-4-2)=0$

$\Leftrightarrow (x-4)(x-6)=0$

$\Leftrightarrow x=4$ hoặc $x=6$

Answer 2

a) 2x.(x - 1) + x.(x - 2) = 3x² - 1

2x² - 2x + x² - 2x - 3x² = -1

-4x = -1

\(x=\frac{1}{4}\)

Vậy \(x=\frac{1}{4}\)

b) (x - 4)² = 2.(x - 4)

(x - 4)² - 2(x - 4) = 0

(x - 4)(x - 4 - 2) = 0

(x - 4)(x - 6) = 0

\(\Rightarrow\) x - 4 = 0 hoặc x - 6 = 0

*) x - 4 = 0

x = 0 + 4

x = 4

*) x - 6 = 0

x = 0 + 6

x = 6

Vậy x = 4; x = 6