Bonjour,
* signifie multiplié par
Rappel:
(a+b)²=a²+2ab+b²
(a-b)²=a²-2ab+b²
(a+b)(a-b)=a²-b²
a(b-c)=ab-ac
A=(2y+3)²-(3y-2)²
=(2y)²+2*2y*3+3²-[(3y)²-2*3y*2+2²]
=4y²+12y+9-(9y²-12y+4)
=4y²+12y+9-9y²+12y-4
= -5y²+24y+5
B=(4y+3)(4y-3)+4(2y-1)
=(4y)²-3²+4*2y-4*1
=16y²-9+8y-4
=16y²+8y-13