Réponse :
salut
1) (8x+1)(5-2x)>(7-8x)(5-2x)
=> (8x+1)(5-2x)-(7-8x)(5-2x)>0
on factorise
(5-2x)(8x+1-7+8x)
(5-2x)(16x-6)
5-2x>0 <=> -2x>-5 <=> x<5/2
16x-6>0 <=> 16x>6 <=> x> 6/16 <=> x> 3/8
S=] 3/8 ; 5/2 [
2) x²+3x-12<x²+5x-13
=> x²+3x-12-x²-5x+13<0
=> -2x+1<0
-2x+1<0 <=> -2x<-1 <=> x> 1/2
S= ] 1/2 ; +oo [
Explications étape par étape