PreCalc

Solve the system by the addition method

-10x^2 + 10y^2-320=0
30x^2 + 6y^2 - 336 = 0

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asked by LT
  1. multiply the first by 3
    -30x^2 + 30y^2 = 960
    30x^2 + 6y^2 = 336, add them
    36y^2 = 1296
    y^2 = 36
    y =±6

    plug y = 6 into one of the equations and find the x
    do the same with y = -6

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    posted by Reiny

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