Question

Phân tích đa thức thành nhân tử a)25x²-70xy+49y²

Answer 1

\(25x^2-70xy+49y^2\\ =25x^2-35xy-35xy+49y^2\\ =25x\left(x-\dfrac{7}{5}y\right)-35y\left(x-\dfrac{7}{5}y\right)\\ =\left(25x-35y\right)\left(x-\dfrac{7}{5}y\right)\\ =5\left(5x-7y\right)\left(x-\dfrac{7}{5}y\right)\)

Answer 2

(5x-7y)^2

Answer 3

=(5x)^2-2*5x*7y+(7y)^2

=(5x-7y)^2