Sagot :
A= (3x-5)²-(3x-5)×(3x+5)
A=9x²-30x+25-[(3x)²-5²]
A=9x²-30x+25-9x²+25
A=-30x+50
(a-b)²=a²-2ab+b²
(a-b)(a+b)=a²-b²
A=9x²-30x+25-[(3x)²-5²]
A=9x²-30x+25-9x²+25
A=-30x+50
(a-b)²=a²-2ab+b²
(a-b)(a+b)=a²-b²