Question

(3x+9)(6x+8) (3x+7y)(3x-7y) (1/3a^2b^2)(-15a^2b^2) (3mn+1)(3mn-1)-8m^2n^2 (x+2)^2-(x+1)(x-1)

(x+y+z)(x+y-z)
(1)(3x+9)(6x+8) (2)(3x+7y)(3x-7y) (3) (1/3a^2b^2)(-15a^2b^2) (4)(3mn+1)(3mn-1)-8m^2n^2 (5) (x+2)^2-(x+1)(x-1) （6)（x+y+z)（x+y-z） 上面的有点不清晰这才是

Answer 1

(1)(3x+9)(6x+8)
=18x^2+24x+54x+72
=18x^2+78x+72

(2)(3x+7y)(3x-7y)
=9x^2-49y^2

(3) (1/3a^2b^2)(-15a^2b^2)
=(-15a^2b^2)/(3a^2b^2)
=-15/3
=-5

(4)(3mn+1)(3mn-1)-8m^2n^2
=9m^2n^2-1-8m^2n^2
=m^2n^2-1

(5) (x+2)^2-(x+1)(x-1)
=x^2+4x+4-(x^2-1)
=x^2+4x+4-x^2+1
=4x+5

（6)（x+y+z)（x+y-z）
=[(x+y)+z] [(x+y)-z]
=(x+y)^2-z^2
=x^2+y^2+2xy-z^2
=x^2+y^2-z^2+2xy

希望可以帮到你、望采纳、