Question

срочно надо!!! помогите плиз​

Answer 1

a) $87^{2} -174*67+67^{2} = (87-67)^{2} = 20^{2} = 400$

$(a-b)^{2} = a^{2} -2ab + b^{2}$

b) $\frac{38^{2}-17^{2} }{47^{2} -361 } = \frac{38^{2}-17^{2} }{47^{2} -19^{2} }= \frac{(38-17)(38+17)}{(47-19)(47+19)} = \frac{21*55}{28*66} = \frac{21*5}{28*6} =\frac{3*5}{4*6} = \frac{5}{4*2} =\frac{5}{8} = 0.625$

$a^{2} -b^{2} = (a+b)(a-b)$