1.计算 (1) (5x-2y)^2+20xy (2)(x-3)^2(x+3)^2 (3) (3x-5)^2-(2x+7)^2 (4)(x+y+1)1.计算 (1) (5x-2y)^2+20xy (2)(x-3)^2(x+3)^2 (3) (3x-5)^2-(2x+7)^2 (4)(x+y+1)(x+y-1)(
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![1.计算 (1) (5x-2y)^2+20xy (2)(x-3)^2(x+3)^2 (3) (3x-5)^2-(2x+7)^2 (4)(x+y+1)1.计算 (1) (5x-2y)^2+20xy (2)(x-3)^2(x+3)^2 (3) (3x-5)^2-(2x+7)^2 (4)(x+y+1)(x+y-1)(](/uploads/image/z/695842-34-2.jpg?t=1.%E8%AE%A1%E7%AE%97+%EF%BC%881%EF%BC%89+%EF%BC%885x-2y%EF%BC%89%5E2%2B20xy+%EF%BC%882%EF%BC%89%EF%BC%88x-3%EF%BC%89%5E2%EF%BC%88x%2B3%EF%BC%89%5E2+%EF%BC%883%EF%BC%89+%EF%BC%883x-5%EF%BC%89%5E2-%EF%BC%882x%2B7%EF%BC%89%5E2+%EF%BC%884%EF%BC%89%EF%BC%88x%2By%2B1%EF%BC%891.%E8%AE%A1%E7%AE%97+%EF%BC%881%EF%BC%89+%EF%BC%885x-2y%EF%BC%89%5E2%2B20xy+%EF%BC%882%EF%BC%89%EF%BC%88x-3%EF%BC%89%5E2%EF%BC%88x%2B3%EF%BC%89%5E2+%EF%BC%883%EF%BC%89+%EF%BC%883x-5%EF%BC%89%5E2-%EF%BC%882x%2B7%EF%BC%89%5E2+%EF%BC%884%EF%BC%89%EF%BC%88x%2By%2B1%EF%BC%89%EF%BC%88x%2By-1%EF%BC%89%EF%BC%88)
1.计算 (1) (5x-2y)^2+20xy (2)(x-3)^2(x+3)^2 (3) (3x-5)^2-(2x+7)^2 (4)(x+y+1)1.计算 (1) (5x-2y)^2+20xy (2)(x-3)^2(x+3)^2 (3) (3x-5)^2-(2x+7)^2 (4)(x+y+1)(x+y-1)(
1.计算 (1) (5x-2y)^2+20xy (2)(x-3)^2(x+3)^2 (3) (3x-5)^2-(2x+7)^2 (4)(x+y+1)
1.计算 (1) (5x-2y)^2+20xy (2)(x-3)^2(x+3)^2
(3) (3x-5)^2-(2x+7)^2 (4)(x+y+1)(x+y-1)
(5)89.8^2 (6)47^2-94×27+27^2
1.计算 (1) (5x-2y)^2+20xy (2)(x-3)^2(x+3)^2 (3) (3x-5)^2-(2x+7)^2 (4)(x+y+1)1.计算 (1) (5x-2y)^2+20xy (2)(x-3)^2(x+3)^2 (3) (3x-5)^2-(2x+7)^2 (4)(x+y+1)(x+y-1)(
1.计算 (1) (5x-2y)^2+20xy
=25x^2-20xy+4y^2+20xy
=25x^2+4y^2
(2)(x-3)^2(x+3)^2
=(x^2-9)^2
=x^4-18x^2+81
(3) (3x-5)^2-(2x+7)^2
=(3x-5+2x+7)(3x-5-2x-7)
=(5x-2)(x-12)
=5x^2-60x-2x+24
=5x^2-62x+24
(4)(x+y+1)(x+y-1)
=(x+y)^2-1
=x^2+2xy+y^2-1
(5)89.8^2
=(90-0.2)^2
=8100-36+0.04
=8064.04
(6)47^2-94×27+27^2
=(47-27)^2
=20^2
=400