Question

(y-5)^2-(y+7)^2 упрастите

Answer 1

${(y - 5)}^{2} - {(y + 7)}^{2} = {y}^{2} - 10y + 25 - ( {y}^{2} + 14y + 49) = {y}^{2} - 10y + 25 - {y}^{2} - 14y - 49 = - 24y - 24$

Answer 2

$\boxed{\bf (a\pm b)^2=a^2\pm 2ab+b^2} \Rightarrow \\ \tt (y-5)^2-(y+7)^2=y^2-10y+25-(y^2+14y+49)=\\ =y^2-10y+25-y^2-14y-49=-24y-24.$