运用平方差公式计算,急!(1) (2/3x-y)(2/3x+y)(2) (xy+1)(xy-1)(3) (2a-3b)(3b+2a) (4) (-2b-5)乘(2b-5)

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运用平方差公式计算,急!(1) (2/3x-y)(2/3x+y)(2)  (xy+1)(xy-1)(3)    (2a-3b)(3b+2a)   (4)    (-2b-5)乘(2b-5)

运用平方差公式计算,急!(1) (2/3x-y)(2/3x+y)(2) (xy+1)(xy-1)(3) (2a-3b)(3b+2a) (4) (-2b-5)乘(2b-5)
运用平方差公式计算,急!
(1) (2/3x-y)(2/3x+y)
(2) (xy+1)(xy-1)
(3) (2a-3b)(3b+2a)
(4) (-2b-5)乘(2b-5)

运用平方差公式计算,急!(1) (2/3x-y)(2/3x+y)(2) (xy+1)(xy-1)(3) (2a-3b)(3b+2a) (4) (-2b-5)乘(2b-5)
1) (2/3x-y)(2/3x+y)
=4/9x^2-y^2
(2) (xy+1)(xy-1)=x^2*y^2-1
(3) (2a-3b)(3b+2a) =4a^2-9b^2
(4) (-2b-5)乘(2b-5)=25-4b^2

(1) (2/3x-y)(2/3x+y)=4x^2/9-y^2
(2) (xy+1)(xy-1)=x^2y^2-1
(3) (2a-3b)(3b+2a)4a^2-9b^2
(4) (-2b-5)乘(2b-5) =25-4b^2

1.4/9x^2-y^2
2.x^2y^2-1
3.4a^2-9b^2
4.-4b^2+25

1、(2/3x)^2-y^2
2、 (xy)^2-1
3、4a^2-9b^2
4、25-4b^2

(1)4/9x2-y2
(2)x2y2-1
(3)4a2-9b2
(4)25-4b2