Bonjour,
B = 4a - 2b(7-4a) -5+3a(4b-1)
4a -14b +8ab -5 + 12ab -3a
= 20ab +a -14b -5
C = 3(7-4a) + 5b(4a - 2)-8a(3-4b)
= 21 - 12a + 20ab -10b -24a + 32ab
= +52ab -36a -10b +21
D= 5- (7a-2b) + 2b(3a - 4) - a(b-1)
= 5 -7a +2b +6ab -8b -ab +a
= ( je te laisse compter)
bonjour
B = 4a - 2b(7-4a) -5+3a(4b-1)
=4a-14b+8ab-5+12ab-3a
=a-14b+20ab-5
C = 3(7-4a) + 5b(4a - 2)-8a(3-4b)
=21-12a+20ab-10b-24a+32ab
=21-36a-10b+52ab
D= 5- (7a-2b) + 2b(3a - 4) - a(b-1)
=5-7a+2b+6ab-8b-ab+a
=5-6a-6b+5ab
