Question

trình bày đầy đủ nha

 

Answer 1

a)   (x+2)² + (x + 1)(x - 1) - x(2x + 5)

    =   x² + 4x +4 + x² - 1 - 2x² - 5x

    = 3 - x

b)    (35x⁶y⁷ - 25x³y⁵): 5x³y⁵ - \(\dfrac{1}{3}x^3y^2\)

    = 7x³y² - 5 - \(\dfrac{1}{3}x^3y^2\)

     = \(\dfrac{20}{3}\)x³y² -5

c)   \(\dfrac{x-3}{x+3}+\dfrac{3}{3-x}+\dfrac{6x}{x^2-9}\)

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

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

= \(\dfrac{x^2-6x+9-3x-9+6x}{x^2-9}\)

= \(\dfrac{x^2-3x}{x^2-9}\)

= \(\dfrac{x\left(x-3\right)}{\left(x-3\right)\left(x+3\right)}\)

=\(\dfrac{x}{x+3}\)