Question

Answer 1

`a) (y - 5)(y+8) - (y + 4)(y-1) `

`= y^2 - 5y + 8y - 40 - (y^2 + 4y - y - 4) `

`= y^2 + 3y - 40 - (y^2 + 3y - 4) `

`= y^2 + 3y - 40 - y^2 - 3y + 4`

`= -36`

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`b) y^4 - (y^2 - 1)(y^2 + 1)` 

`= y^4 - [(y^2)^2 - 1^2]`

`= y^4 - (y^4 - 1)`

`= y^4 - y^4 + 1`

`= 1`

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Answer 2

a) \(\left(y-5\right)\left(y+8\right)-\left(y+4\right)\left(y-1\right)\)

\(=y^2+8y-5y-40-\left(y^2-y+4y-4\right)\)

\(=y^2+3y-40-y^2+y-4y+4\)

\(=-36\)

Vậy...