СРОЧНО! 15-(a+3)(a-3)= (a+b)(a-b)-(a-b)^2= (2a+1)^2+(1-2a)(1+2a)= 2х-(5-3х-4)=х-5
15-(a+3)(a-3)=15-a²+9=-a²+24 (a+b)(a-b)-(a-b)^2=a²-b²-a²+2ab-b²=-2b²+2ab (2a+1)^2+(1-2a)(1+2a)=4a²+4a+1+1-4a²=4a+2 2х-(5-3х-4)=х-5 2x-5+3x+4=x-5 5x-x=-5-4+5 4x=-4|:4 x=-1