①4(a+b)²-9a+9b②x²/25-y²/16③-3x+6x²-3X的³④0.1a的四次方+0.8a²+1.6⑤[(3x-7)²-(x+5)²]÷(4x-24)第一题错掉了、是①4(a-b)²-9a+9b

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①4(a+b)²-9a+9b②x²/25-y²/16③-3x+6x²-3X的³④0.1a的四次方+0.8a²+1.6⑤[(3x-7)²-(x+5)²]÷(4x-24)第一题错掉了、是①4(a-b)²-9a+9b
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①4(a+b)²-9a+9b②x²/25-y²/16③-3x+6x²-3X的³④0.1a的四次方+0.8a²+1.6⑤[(3x-7)²-(x+5)²]÷(4x-24)第一题错掉了、是①4(a-b)²-9a+9b
①4(a+b)²-9a+9b
②x²/25-y²/16
③-3x+6x²-3X的³
④0.1a的四次方+0.8a²+1.6
⑤[(3x-7)²-(x+5)²]÷(4x-24)
第一题错掉了、是①4(a-b)²-9a+9b

①4(a+b)²-9a+9b②x²/25-y²/16③-3x+6x²-3X的³④0.1a的四次方+0.8a²+1.6⑤[(3x-7)²-(x+5)²]÷(4x-24)第一题错掉了、是①4(a-b)²-9a+9b
1.=4(a-b)(a+b)-9(a-b)
=(a-b)*(4a+4b-9)
2.x²/25-y²/16
=(x/5)²-(y/4)²
=(x/5-y/4)(x/5+y/4)
3.3x+6x²-3X的³
=-3x*(1-2x+x²)
=-3x*(x-1)²
4.0.1a的四次方+0.8a²+1.6
=0.1(a的四次方+8a²+16)
=0.1(a²的2次方+2*4a²+4²)
=0.1(a²+4)的2次方
⑤[(3x-7)²-(x+5)²]÷(4x-24)
={[(3x-7)-(x+5)]*[(3x-7)+(x+5)]}÷[4(x-6) ]
=[(4x-2)]*(2x-12)]÷[4(x-6) ]
=[2(2x-1)]*2(x-6)]÷[4(x-6) ]
=(2x-1)