解方程,(50—2X)(50—X)=300

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解方程,(50—2X)(50—X)=300
解方程,(50—2X)(50—X)=300

解方程,(50—2X)(50—X)=300

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原式可得:
2500-150X+2X²=300
2200+2X²-150X=0
1100+X²-75X=0
(X-20)(X-55)=0
X=20或55

2500-50x-100x+2x^2=300
2x^2-150x+2200=0
x^2-75x+1100=0
(x-37.5)^2-1406.25+1100=0
(x-37.5)^2=306.25
x-37.5=±17.5
x=37.5±17.5
x=20或x=55

(50-2x)(50-x)=300
即:2500-150x+2x^2=300
/2
x^2-75x+1250=150
-1250
x^2-75x=-1100
+(75/2)^2
x^2-2(75/2)x+(75/2)^2=(75/2)^2-1100
[x-(75/2)]^2=(75/2)^2-1100
x=[(75/2)^2-1100]^(1/2)+(75/2)

2X2—100X—50X+2500=300

2X2—150X+2200=0

(X—20)(X—55)=0

X=20或55


(50-2x)(50-x)=300
2500-100x-50x+2x²=300
2x²-150x+2200=0
x²-75x+1100=0
十字相乘法
1 -20
×
1 -55
(x-20)(x-55)=0
x1=20
x2=55