Question by Fake Love - Discuss with MathYouLike

Fake Love

23/11/2017 at 15:19

Rút gọn các biểu thức sau :

a) $(x + 2) (x - 2) - (x - 3) (x + 1)$ ;

b) ${(2 x + 1)}^{2} + {(3 x - 1)}^{2} + 2 (2 x + 1) (3 x - 1)$

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Lạnh Lùng Boy 23/11/2017 at 15:21

a) (x+2)(x−2)−(x−3)(x+1)(x+2)(x−2)−(x−3)(x+1)

=x^2−22−(x^2+x−3x−3)x^2−22−(x^2+x−3x−3)

=x^2−4−x^2−x+3x+3x^2−4−x^2−x+3x+3

=2x−12x−1 ;

b) (2x+1)^2+(3x−1)^2+2(2x+1)(3x−1)(2x+1)^2+(3x−1)^2+2(2x+1)(3x−1)

=(2x+1)^2+2.(2x+1)(3x−1)+(3x−1)^2(2x+1)^2+2.(2x+1)(3x−1)+(3x−1)^2

=[(2x+1)+(3x−1)]^2[(2x+1)+(3x−1)]^2

= (2x+1+3x−1)^2(2x+1+3x−1)^2

=(5x)^2=25x^2
Fake Love selected this answer.

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