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Solve the system: x^2 + y^2 = 17 x - 4y = 0

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kristenmarieb... | Student, Grade 10 | Valedictorian

Posted July 10, 2013 at 5:23 PM via web

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Solve the system:

x^2 + y^2 = 17

x - 4y = 0

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aruv | High School Teacher | Valedictorian

Posted July 10, 2013 at 5:32 PM (Answer #1)

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`x^2+y^2=17`    (i)

`x-4y=0`         (ii)

solve (ii) for x

`x=4y`    

Substitute x=4y in (i)

`(4y)^2+y^2=17`

`16y^2+y^2=17`

`17y^2=17`

`y^2=1`

`y=+-1`    

Thus

`x=+-4`

So solution set is (4,1)  and (-4,-1)

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