Question

Answer 1

`x^2 -2xy+y^2-81`

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

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

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

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`x^3 +y^3 +21x+21` gì đó bạn?

Answer 2

\(a)x^2-2xy+y^2-81\\=(x^2-2xy+y^2)-81\\=(x-y)^2-9^2\\=(x-y-9)(x-y+9)\\---\\b)x^3+y^3+21x+21y\\=(x^3+y^3)+(21x+21y)\\=(x+y)(x^2-xy+y^2)+21(x+y)\\=(x+y)(x^2-xy+y^2+21)\)

#\(Toru\)

Answer 3

a) x² - 2xy + y² - 81

= (x² - 2xy + y²) - 9²

= (x - y)² - 9²

= (x - y - 9)(x - y + 9)

l) x³ + y³ + 21x + 21y

= (x³ + y³) + (21x + 21y)

= (x + y)(x² - xy + y²) + 21(x + y)

= (x + y)(x² - xy + y² + 21)