1) développer et réduire A et B
A=9a²-4+(3a+2)(a-3)
A=9a²-4+(3a²-6a+2a-6)
A=9a²-4+3a²-6a+2a-6
A=9a²+3a²-6a+2a-4-6
A=10a²-4a-10
B=(4x-5)²-(x+3)²
B=16x²-40x+25-(x²+6x+9)
B=16x²-40x+25-x²-6x-9
B=16x²-x²-40x-6x+25-9
B=15x²-46x+16
2)factoriser A et B
A=9a²-4+(3a+2)(a-3)
A=(3a)²-2²+(3a+2)(a-3)
A=(3a-2)(3a+2)+(3a+2)(a-3)
A=(3a+2)[(3a-2)+(a-3)]
A=(3a+2)(3a-2+a-3)
A=(3a+2)(4a-5)
B=(4x-5)²-(x+3)²
B=[(4x-5)-(x+3)][(4x-5)+(x+3)]
B=(4x-5-x-3)(4x-5+x+3)
B=(3x-8)(5x-2)