计算1.(3b+2a)(2a-3b) 2.(3m-2n)(-3m-2n) 3.(xy-5)(-xy-5) 4.(-2x)²-(-2x+3)(-2x-3)

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计算1.(3b+2a)(2a-3b) 2.(3m-2n)(-3m-2n) 3.(xy-5)(-xy-5) 4.(-2x)²-(-2x+3)(-2x-3)

计算1.(3b+2a)(2a-3b) 2.(3m-2n)(-3m-2n) 3.(xy-5)(-xy-5) 4.(-2x)²-(-2x+3)(-2x-3)
计算1.(3b+2a)(2a-3b) 2.(3m-2n)(-3m-2n) 3.(xy-5)(-xy-5) 4.(-2x)²-(-2x+3)(-2x-3)

计算1.(3b+2a)(2a-3b) 2.(3m-2n)(-3m-2n) 3.(xy-5)(-xy-5) 4.(-2x)²-(-2x+3)(-2x-3)
1.(3b+2a)(2a-3b)
=9b²-4a²
2.(3m-2n)(-3m-2n)
=4n²-9m²
3.(xy-5)(-xy-5)
=25²-x²y²
4.(-2x)²-(-2x+3)(-2x-3)
=4x²-4x²+9
=9