Math q

表面上是得了分,但若是靠抄襲別人文字而得來,根據沒有絲毫意思!

1) y=x+1 --- ( 1 )

x2+y2=3 --- ( 2 )

Put ( 1 ) into ( 2 ),

x^2 + ( x + 1 )^2 = 3

x^2 + x^2 + 2x + 1 = 3

2x^2 + 2x - 2 = 0

x^2 + x - 1 = 0

x = ( - 1 + sqr 5 ) / 2 or ( - 1 - sqr 5 ) / 2

y = ( 1 + sqr 5 ) / 2 or ( 1 - sqr 5) / 2

2) 4x - 2y = 2

y = 2x - 1 --- ( 1 )

x^2 - y^2 + 3 = 0 --- ( 2 )

Put ( 1 ) into ( 2 ),

x^2 - ( 2x - 1 )^2 + 3 = 0

x^2 - 4x^2 + 4x - 1 + 3 = 0

3x^2 - 4x - 2 = 0

x = ( 2 + sqr 10 ) / 3 or ( 2 - sqr 10 ) / 3

y = ( 1 + 2 sqr 10 ) / 3 or ( 1 - 2 sqr 10 ) / 3






2007-12-03 22:58:49 補充：
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