Question

Найдите алгебраическую сумму многочленов (8X - 7y)² - (70x² + 45y²)-(-15х²+48ху)​

Answer 1

$\displaystyle\bf\\(8x-7y)^{2} -(70x^{2}+45y^{2} )-(-15x^{2} +48xy)=\\\\=(8x)^{2} -2\cdot 8x\cdot 7y+(7y)^{2} -70x^{2} -45y^{2}+15x^{2} -48xy=\\\\=64x^{2} -112xy+49y^{2} -70x^{2} -45y^{2}+15x^{2} -48xy=\\\\=\underbrace{(64x^{2} -70x^{2} +15x^{2} )}_{9x^{2} }-\underbrace{(112xy+48xy)}_{160xy}+\underbrace{(49y^{2}-45y^{2} )}_{4y^{2}} =\\\\=9x^{2} -160xy+4y^{2}$