（x1-x2）²和（x1+x2）²等于?

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（x1-x2）²和（x1+x2）²等于?
（x1-x2）²和（x1+x2）²等于?

（x1-x2）²和（x1+x2）²等于?
(x1-x2)²
=x1²-2x1x2+x2²
=(x1²+2x1x2+x2²)-4x1x2
=(x1+x2)²-4x1x2
=(-b/a)²-4c/a
=b²/a²-4c/a
=(b²-4ac)/a²
(x1+x2)²
=(-b/a)²
=b²/a²