Question

Упростить выражение 1). 7(x+8) + (x+8)(x-8) 2). (x-3)(3+x)+(x-3)² 3). (y-5)²-(y+7)² 4). (x+3)(x-3) - x² + 2x​

Answer 1

$\displaystyle\bf\\1)\\\\7(x+8)+(x+8)(x-8)=7x+56+x^{2} -64=x^{2} +7x-8\\\\\\2)\\\\(x-3)(3+x)+(x-3)^{2} =x^{2} -9+x^{2} -6x+9=2x^{2} -6x\\\\\\3)\\\\(y-5)^{2} -(y+7)^{2} =y^{2} -10y+25-(y^{2}+14y+49)=\\\\=y^{2} -10y+25-y^{2} -14y-49=-24y-24\\\\\\4)\\\\(x+3)(x-3)-x^{2} +2x=x^{2} -9-x^{2} +2x=2x-9$