Réponses

2013-11-21T16:06:19+01:00
A) x+5 > 0 => x > - 5  et 2x+7 > 0 => x > -7/2  donc x > -7/2
b) Aire = A(x) = (2x+7)² - (x+5)² 
c) A(x) = 4x² + 28x + 49 - x² - 10x - 25 = 3x² + 18x + 24
d) A(x) = (2x+7-x-5)(2x+7+x+5) = (x+2)(3x+12)
e) A(0) = 24  ;  A(2) = 4.18 = 72 ; A(3/2) = 7/2.33/2 =  221/4
f) périmètre = P(x) = 2(2x+7) + 2(2x+7-x-5) = 4x+14 + 2x + 4 = 6x+ 18 
P(x) = 18 ; P(2) = 12 + 18 = 30 ; P(3/2) = 9 + 18 = 27