Sagot :
A = (9x-4)(-2x+1)
= 9xX(-2x)+9xX1 -4X(-2x)-4x1
= -18x^2 +9x +8x -4
= -18^2 + 17x -4
*x = x
X : signe demultiplication
B = 15x-(2x+5)^2
= 15x- ((2x)^2 + 2 X 2x X 5 + 5^2)
= 15x - (4x^2 + 20x + 25)
=15x - 4x^2 - 20x -25
= 4x^2 -5x - 25
Voilà :)
= 9xX(-2x)+9xX1 -4X(-2x)-4x1
= -18x^2 +9x +8x -4
= -18^2 + 17x -4
*x = x
X : signe demultiplication
B = 15x-(2x+5)^2
= 15x- ((2x)^2 + 2 X 2x X 5 + 5^2)
= 15x - (4x^2 + 20x + 25)
=15x - 4x^2 - 20x -25
= 4x^2 -5x - 25
Voilà :)
A) (9x-4)(-2x+1)
=-18x²+8x+9x-4
=-18x²+17x-4
B)15x-(2x+5)²
=15x-4x²-20x-25
=-4x²-5x-25
=-18x²+8x+9x-4
=-18x²+17x-4
B)15x-(2x+5)²
=15x-4x²-20x-25
=-4x²-5x-25