Question

①x的m﹢3次方﹢2x的m﹢2次方y﹢x的m﹢1次方y² ②a³﹣4a²﹢4a ③已知x﹣

Answer 1

②：a^3-4a^2+4a=a(a-2)^2 ③：x^2-y^2=(x+y)(x-y)因为x^2-y^2=15,x-y=5,所以x+y=3,所以x=4,y=-1 ④：x^2-y^2-(x+y)=(x+y)(x-y-1) ⑤：原式可得m(m-n)+n(m-n)=15,则解得m^2-n^2=15,因为m,n均为正整数,所以m=8,n=7 ⑥12a^2b^3+6a^2b^2-18a^3b^2=6ab(2b+1-3a) ⑦原式解得9mn(-3m+n-2) ⑧原式解得3(x-3)(3m-5n) ⑨原式解得3（a-b+1）(x+y+z)