Question

phân tích đa thức thành nhân tử: 49(y-4)^2-9(y+2)^2

Answer 1

\(49\left(y-4\right)^2-9\left(y+2\right)^2\)

\(=7^2\left(y-4\right)^2-3^2\left(y+2\right)^2\)

\(=\left[7\left(y-4\right)\right]^2-\left[3\left(y+2\right)\right]^2\)

\(=\left[7\left(y-4\right)-3\left(y+2\right)\right]\left[7\left(y-4\right)+3\left(y+2\right)\right]\)

\(=\left(7y-28-3y-6\right)\left(7y-28+3y+6\right)\)

\(=\left(4y-34\right)\left(10y-22\right)\)

Answer 2

`49(y-4)²-9(y+2)²`

`= [7(y-4)]²-[3(y+2)]²`

`= [7(y-4)+3(y+2)]-[7(y-4)-3(y+2)]`

`= (7y-28+3y+6)(7y-28-3y-6)`

`= (10y-22)(4y-34)`