Question

a/ (x+1) ² - (x-1) ² - 2(x+1)(x-1)

b/ 5(x+2)(x-) - 1/2 . (6-8x) ² + 17

c/ (3x+1) ² - 2(3x+1)(3x+5)+(3x+5) ²

Answer 1

Đề là gì vậy ạ?

Answer 2

a) \(\left(x+1\right)^2-\left(x-1\right)^2-2\left(x+1\right)\left(x-1\right)\)

\(=\left(x^2+2x+1^2\right)-\left(x^2-2x+1^2\right)-2.\left(x^2-1^2\right)\)

\(=x^2+2x+1-x^2+2x-1-2x^2+2\)

\(=4x-2x^2+2\)

b) Check lại đề nha! Thiếu rồi

c) \(\left(3x+1\right)^2-2\left(3x+1\right)\left(3x+5\right)+\left(3x+5\right)^2\)

\(=\left(9x^2+2.3x.1+1^2\right)-2.\left[3x\left(3x+5\right)+1\left(3x+5\right)\right]+\left(9x^2+2.3x.5+5^2\right)\)

\(=9x^2+6x+1-2\left(9x^2+15x+3x+5\right)+9x^2+30x+25\)

\(=9x^2+6x+1-18x^2-30x-6x-10+9x^2+30x+25\)

\(=16\)

P/s: Ko chắc!