Réponses

2013-12-17T19:24:18+01:00
1) a) pour x=3 BC=6cm et AE=8cm
A(ABFE)=8*8=64 cm^2
A(ABCD)=6*8=48 cm^2
A(totale)=2*64+4*48=320 cm^2

b) V=8*8*6=384 cm^3

2) a) A(ABFE)=(x+5)(x+5)=(x+5)^2=x^2+10x+25

b) A(ABCD)=2x(x+5)=2x^2+10x

c) A(totale)=2(x+5)^2+4*2x(x+5)=(x+5)(2x+10+8x)=(x+5)(10x+10)=10(x+5)(x+1)

3) V=2x(x+5)^2=2x(x^2+10x+25)=2x^3+20x^2+50x