Question

求解法啊

Answer 1

14,原式＝9X^2－y^2+Xy+y^2
=9X^2+XY
15.原式=(m^2-9)*(m^2+9)
=m^4-81

Answer 2

14.
(3x-y)(3x+y)+y(x+y)
=9x²-y²+xy+y²
=9x²+xy

15.
(m+3)(m-3)(m²+9)
=(m²-9)(m²+9)
=m⁴-81

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