Pouvez m’aider ex 8 svp merciii

a. (x+4)² = x²+ 2*4x+16
= x² + 8x + 16

b. (x-5)²= x²-2*5x+25
= x² - 10x + 25

c. (1+3x)(1-3x)= 1 -3x + 3x - 9x²
= 1 - 9x²

d. (5+2x)(-2x+5) = (5+2x)(5-2x)
= 25 - 10x + 10x - 4x²
= 25 - 4x²