1. A = -15x²+6x+25x-10-(9x²-30x+25)
A = -15x²+31x-10-9x²+30x-25
A = -24x²+61x-35
2. A = (3x-5)[(-5x+2)-(3x-5)]
A = (3x-5)(-5x+2-3x+5)
A = (3x-5)(-8x+7)
3. x=5/3
A = (3*(5/3)-5)(-8*(5/3)+7)
A = (5-5)((-40/3)+7)
A = 0*((-40/3)+7) = 0
4. (3x-5)(-8x+7) = 0
3x-5=0 ou -8x+7=0
3x=5 -8x=-7
x=5/3 x=-7/-8=7/8