Bonsoir,
1) Calculer:
A= 7/3 -2/3 x3/5= 7/3- 2/5= (7x5-2x3)/(3x5)= 29/15
B= [tex]\frac{2}{8}[/tex] x 10⁷⁻⁸⁺²= 0.25x 10¹= 25/10= 5/2
2) C(x)= x²-25+4(x+5)²
Développer C(x):
C(x)= x²-25+4(x+5)²
C(x)= x²-25+4(x+5)(x+5)
C(x)= x²-25+4(x²+10x+25)
C(x)= x²-25+4x²+40x+100
C(x)= 5x²+40x+75
Calculer C(5)
C(5)= 5(5)²+40(5)+75= ... calcule
Démontre que C(x)= 5(x+5)(x+3)
On factorise
C(x)= x²-25+4(x+5)²
C(x)= (x-5)(x+5)+4(x+5)(x+5)
C(x)= (x+5)(x-5+4(x+5))
C(x)= (x+5)(x-5+4x+20)
C(x)= (x+5)(5x+15)
C(x)= 5(x+5)(x+3)
Simplifier:
1/(a-1) - 2/(a+1)= (a+1-2(a-1)/(a-1)(a+1)= (a+1-2a+2)/(a²-1)= (-a+3)/(a²-1)
