What should be taken away from $3x^2-4y^2+5xy+20$ to obtain $– x^2-y^2+6xy+20$?

AcademicMathematicsNCERTClass 7

Given: Terms $3x^2-4y^2+5xy+20$ and $– x^2-y^2+6xy+20$.

To do: This is to find out what should be taken from $3x^2-4y^2+5xy+20$ to get $- x^2-y^2+6xy+20$.

Solution: Let us assume $a$ be the required term


Then,


$3x^2-4y^2+5xy+20-a=-x^2-y^2+6xy+20$


$a=3x^2-4y^2+5xy+20-(-x^2-y^2+6xy+20)$


$a=3x^2-4y^2+5xy+20+x^2+y^2-6xy-20$


$a=3x^2+x^2-4y^2+y^2+5xy-6xy+20-20$


$a=4x^2-3y^2-xy$


Therefore, $4x^2-3y^2-xy$ should be taken from $3x^2-4y^2+5xy+20$ to get $- x^2-y^2+6xy+20$.

raja
Updated on 10-Oct-2022 13:38:20

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