搜搜考试网两道数学奥赛题（过程详细）
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两道数学奥赛题（过程详细）
已知3a=4b,则2a^2-3ab+b^2/a^2-b^2=________ 2.已知x^-6x+8y+y^+25=0,求根号下2x-3y的值
已知3a=4b,则2a^2-3ab+b^2/a^2-b^2=________ 2.已知x^-6x+8y+y^+25=0,求根号下2x-3y的值
3a=4b
a=4/3b
2a^2-3ab+b^2/a^2-b^2
=(a-b)(2a-b)/(a+b)(a-b)
=2a-b/a+b
=(2*4/3b-b)/(4/3b+b)
=(5/3)/(7/3)
=5/7
x^-6x+8y+y^+25=0
(x-3)^2+(y+4)^2=0
(x-3)^2=0
x=3
(y+4)^2=0
y=-4
根号下2x-3y
=根号下2*3-3(-4)
=根号下6+12
=3根号下2
a=4/3b
2a^2-3ab+b^2/a^2-b^2
=(a-b)(2a-b)/(a+b)(a-b)
=2a-b/a+b
=(2*4/3b-b)/(4/3b+b)
=(5/3)/(7/3)
=5/7
x^-6x+8y+y^+25=0
(x-3)^2+(y+4)^2=0
(x-3)^2=0
x=3
(y+4)^2=0
y=-4
根号下2x-3y
=根号下2*3-3(-4)
=根号下6+12
=3根号下2