Question

rút gọn biểu thức
(x-4)² - 2(x-4)(x+5) + (x+5)²

Answer 1

(x-4)² - 2(x-4)(x+5) + (x+5)²

⁼(x² - 2.x.4 + 4²) - 2(x²+5x-4x-20)+(x²+2.x.5+5²)

=x² - 8x + 16 - 2x²-10x+8x+40+x²+10x+25

=(x² - 2x² +x²)+(- 8x+8x+10x)+(16+40+25)

=0+0+81=81

Chúc bn học tốt

Answer 2

\(\left(x-4\right)^2-2\left(x-4\right)\left(x+5\right)+\left(x+5\right)^2\)

\(=\left[\left(x-4\right)-\left(x+5\right)\right]=\left(x-4-x-5\right)^2=\left(-1\right)^2=1\)