Bonjour,

Factoriser:

A= 5(x-4); B= x(x+14); C= 3(4x+3); D= 7x(x-1); E= 3(8+x); F= x²(x-13)

On considère M= (3x-10)²-(3x-10)(2x-7)

Développer M:

9x²-30x-30x+100-(6x²-20x-21x+70)= 9x²-60x+100-(6x²-41x+70)

= 9x²-60x+100-6x²+41x-70= 3x²-19x+30

Factoriser M:

M= (3x-10)²-(3x-10)(2x-7)

M= (3x-10)(3x-10 - 2x + 7)

M= (3x-10)(x-3)

Calcul de M:

M(20)= 3(20)²-19(20)+30= 3(400)-380+30= 850

M(3)=  (3(3)-10)(3-3)= 0   **3-3= 0