Question

1 thực hiện phép tính

a) x.(y+5)

b) (x-3)^2+2x.(x-3)

2 rút gọn

a) 2^2b/6a^3b^2

b) 2x-6/x^2-9

c)x^2-2x/x^2+x-6

Answer 1

1a) x.(y+5) = xy + x5

b)(x-3)² + 2x(x-3)= (x² - 2x3+3²) + (2x² -6x)

= x² - 6x + 9 + 2x²-6x

= (x²+2x²) +(-6x-6x) +9

=3x² - 12x +9

Answer 2

Bài 1:

a) x(y + 5)

= xy + 5x

b) (x - 3)² + 2x(x - 3)

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

= (x - 3)(3x - 3)

Bài 2:

a) \(\dfrac{2^2b}{6a^3b^2}=\dfrac{4b}{6a^3b^2}=\dfrac{2}{3a^3b}\)

b) \(\dfrac{2x-6}{x^2-9}=\dfrac{2\left(x-3\right)}{\left(x-3\right)\left(x+3\right)}=\dfrac{2}{x+3}\)

c) \(\dfrac{x^2-2x}{x^2+x-6}=\dfrac{x\left(x-2\right)}{x^2-2x+3x-6}=\dfrac{x\left(x-2\right)}{x\left(x-2\right)+3\left(x-2\right)}=\dfrac{x\left(x-2\right)}{\left(x-2\right)\left(x+3\right)}=\dfrac{x}{x+3}\)