Evaluate
20y^{2}-15xy-7x^{2}
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20y^{2}-15xy-7x^{2}
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2x^{2}-11xy+7y^{2}-4xy-9x^{2}+13y^{2}
To find the opposite of 4xy+9x^{2}-13y^{2}, find the opposite of each term.
2x^{2}-15xy+7y^{2}-9x^{2}+13y^{2}
Combine -11xy and -4xy to get -15xy.
-7x^{2}-15xy+7y^{2}+13y^{2}
Combine 2x^{2} and -9x^{2} to get -7x^{2}.
-7x^{2}-15xy+20y^{2}
Combine 7y^{2} and 13y^{2} to get 20y^{2}.
2x^{2}-11xy+7y^{2}-4xy-9x^{2}+13y^{2}
To find the opposite of 4xy+9x^{2}-13y^{2}, find the opposite of each term.
2x^{2}-15xy+7y^{2}-9x^{2}+13y^{2}
Combine -11xy and -4xy to get -15xy.
-7x^{2}-15xy+7y^{2}+13y^{2}
Combine 2x^{2} and -9x^{2} to get -7x^{2}.
-7x^{2}-15xy+20y^{2}
Combine 7y^{2} and 13y^{2} to get 20y^{2}.
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