Exercice 3 du dm que j'arrive pas

a =(x+2)(x-5)
pour x =3
a =(3+2)(3-5)
a = 5 *-2
a = -10

a =(x+2)(x-5)
pour x = -4
a = (-4+2)(-4-5)
a = -2 * -9
a = 18

b = x²-3x-10
pour x = 3
b = 3²-3*3-10
b = 9-9 -10
b = -10


b = x²-3x-10
pour x = -4
b =  -4² -3*-4 -10
b = 16 +12 -10
b =28-10
b = 18

on constate que A = B

2/ pour x = 2
 a =(x+2)(x-5)
a = 2+2) (2-5)
a = 4 *-3
a = -12

b = x²-3x-10
b = 2² -3*2 -10
b = 4 -6-10
b =4-16
b = -12