Question

Спростіть вираз: (14xy-2y^2 +13x^2)-(-16y^2-5ху+4х^2);
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Answer 1

$\displaystyle\bf\\(14xy-2y^{2} +13x^{2} )-(-16y^{2} -5xy+4x^{2} )=\\\\\\=14xy-2y^{2} +13x^{2} -16y^{2} +5xy-4x^{2} =\\\\\\=\underbrace{(13x^{2} -4x^{2} )}_{9x^{2} }+\underbrace{(14xy+5xy)}_{19xy}-\underbrace{(2y^{2} +16y^{2} )}_{18y^{2} }=\\\\\\=\boxed{9x^{2} +19xy-18y^{2}}$