國二數學4之1 (x-5)(x+1)/2=x(x-7)/3?
回答 (2)
(x-5)(x+1)/2=x(x-7)/3
3(x^2-4x-5)=2(x^2-7x)
3x^2-12x-15=2x^2-14x
x^2+2x-15=0
(x-3)(x+5)=0
x=3 or x=-5
Sol
(x-5)(x+1)/2=x(x-7)/3
3(x-5)(x+1)=2x(x-7)
3(x^2-4x-5)=2(x^2-7x)
3x^2-12x-15=2x^2-14x
x^2+2x-15=0
(x-3)(x+5)=0
x=3 or x=-5
收錄日期: 2021-04-18 14:16:37
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