计算:(1)x²-(x三次y-2x²y²)÷xy (2)x(x+2)(x-2)-(x-4)(x²-1)(3)、(a-2b)²-2(a+b)(a-3b)(4)简便方法98²-97*99注明:这里每小题起码两步,
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计算:(1)x²-(x三次y-2x²y²)÷xy(2)x(x+2)(x-2)-(x-4)(x²-1)(3)、(a-2b)²-2(a+b)(a-3b)(
计算:(1)x²-(x三次y-2x²y²)÷xy (2)x(x+2)(x-2)-(x-4)(x²-1)(3)、(a-2b)²-2(a+b)(a-3b)(4)简便方法98²-97*99注明:这里每小题起码两步,
计算:
(1)x²-(x三次y-2x²y²)÷xy (2)x(x+2)(x-2)-(x-4)(x²-1)
(3)、(a-2b)²-2(a+b)(a-3b)
(4)简便方法98²-97*99
注明:这里每小题起码两步,
计算:(1)x²-(x三次y-2x²y²)÷xy (2)x(x+2)(x-2)-(x-4)(x²-1)(3)、(a-2b)²-2(a+b)(a-3b)(4)简便方法98²-97*99注明:这里每小题起码两步,
(1)x²-(x三次y-2x²y²)÷xy
=x² - xy(x² - 2xy) ÷xy
=x² - (x² - 2xy)
=x² - x² + 2xy
=2xy
.
(2)x(x+2)(x-2)-(x-4)(x²-1)
=x(x²-4) - (x³-x-4x²+4)
=x³-4x² - x³+x+4x²-4
=x-4
.
(3)、(a-2b)²-2(a+b)(a-3b)
=a²-4ab+4b² - 2(a²-2ab-3b²)
=a²-4ab+4b² - 2a² +4ab+6b²
=-a²+10b²
(4)简便方法:
98²-97*99=98²- (98-1)*(98+1)=98²-(98²-1)=98²-98²+1=1