Question

(xy-5).(xy+2)+3(xy-2)(xy+2)-(3xy-\(\dfrac{1}{2}\))²+5x²y²

Answer 1

`(xy-5)(xy+2)+3(xy-2)(xy+2)-(3xy-1/2)^2 +5x^2y^2`

`=(xy+2)(xy-5+3xy-6)-(9x^2y^2-3xy+1/4)+5x^2y^2`

`=(xy+2)(4xy-11)-9x^2y^2+3xy-1/4+5x^2y^2`

`=4x^2y^2-11xy+8xy-22-4x^2y^2+3xy-1/4`

`=-89/4`

Answer 2

Ta có: \(\left(xy-5\right)\left(xy+2\right)+3\left(xy-2\right)\left(xy+2\right)-\left(3xy-\dfrac{1}{2}\right)^2+5x^2y^2\)

\(=x^2y^2-3xy-10+3x^2y^2-12-\left(9x^2y^2-3xy+\dfrac{1}{4}\right)+5x^2y^2\)

\(=9x^2y^2-3xy-22-9x^2y^2+3xy-\dfrac{1}{4}\)

\(=\dfrac{-89}{4}\)