Question

phân tích thành nhân tử

\(x^2 -8xy+7y^2\)

\(x^2 -9xy+14y^2\)

\(x^2 -11xy+18y^2\)

Answer 1

`@` `\text {Ans}`

`\downarrow`

`x^2 - 8xy + 7y^2`

`= x^2 - xy - 7xy + 7y^2`

`= (x^2 - xy) - (7xy - 7y^2)`

`= x(x - y) - 7y(x - y)`

`= (x - 7y)(x - y)`

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`x^2 - 9xy + 14y^2`

`= x^2 - 2xy - 7xy + 14y^2`

`= (x^2 - 2xy) - (7xy - 14y^2)`

`= x(x - 2y) - 7y(x - 2y)`

`= (x - 7y)(x - 2y)`

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`x^2 - 11xy + 18y^2`

`= x^2 - 2xy - 9xy + 18y^2`

`= (x^2 - 2xy) - (9xy - 18y^2)`

`= x(x - 2y) - 9y(x - 2y)`

`= (x - 9y)(x - 2y)`

Answer 2

a: =x^2-xy-7xy+7y^2

=x(x-y)-7y(x-y)

=(x-y)(x-7y)

b: =x^2-2xy-7xy+14y^2

=x(x-2y)-7y(x-2y)

=(x-2y)(x-7y)

c: =x^2-2xy-9xy+18y^2

=x(x-2y)-9y(x-2y)

=(x-2y)(x-9y)