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1.2345² + 0.7655² + 2.469 x 0.7655
=1.2345² + 0.7655² + 2x1.2345 x 0.7655
=(1.2345+0.7655)²
=2²
=4
50² - 49² +48² -47² +````````+2² - 1
=(50+49)(50-49)+(48+47)(48-47)+……+(2+1)(2-1)
=(50+49)x1+(48+47)x1+……+(2+1)x1
=50+49+48+47+……+2+1
=(50+1)+(49+2)+……+(26+25)
=51*25
=204
9X² +6X =5X
9X²+X=0
X(9X+1)=0
X=0,X=-1/9
X²= (3X+1)²
X=3X+1或X=-(3X+1)
X=-1/2,X=-1/4
1年前
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