bonjour,
exo 7 :
B = (x²/4-6xy/4+9y²/4)+(x²/4-3xy/4+3xy/4+3xy/4-9y²/4)+x²/2
= x²/4 - 6xy/4 + 9y²/4 +x²/4 -9y²/4 + x²/2
= 2x²/4 -6xy/4 =
= (x²-3xy)/2
1) dev et réduis :
4a²+4ab+b²-(a²-4ab+b²)-3(a²-b²) =
4a²+4ab+b²-a²+4ab-b²-3a²+3b² =
8ab+3b²
si ab = 2
A = 8*2+3b² = 16+3b²
exo 8 :
[3a(a)-b(b)-2c(c)-3(a²-b²-c²)]/3abc =
(3a²-b²-2c²-3a²+3b²+3c²)/3abc =
2b²+c²/3abc
C = [2(2)²+(4/3)²]/3(2/3*2*4/3)
= (4+16/9)/3*16/9
= 52/9 divisé par 48/9
= 52:48 = 13/12
