Réponse :
pour x=2
on a
A=4x+7 alors A = 4*2 + 7 = 8 +7 = 15
B=3(4x-6) alors B = 3(4*2 -6) = 3(8-6) = 3*2 = 6
C=2(3x+5)-4(5x-7) alors C = 2(3*2 + 5) - 4(5*2 - 7) = 2(6+5)-4(10-7)
<=> C = 2 * 11 - 4*3
<=> C = 22-12
<=> C =10
D=(5x-6) (-2x+8) alors D = (5*2 -6)(-2*2 +8) = (10 -6)(-4+8)
<=> D = 4*4
<=> D =16
E=5x2²-8x-6 alors E = 5*(2²) - 8*2 -6 = 5*4 - 16 -6 = 20 -22
<=> D = -2
j'espère avoir aidé!
