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find the zeros of each equation?

2x^2+8x-30=x+3

please explain how to do it step by step, for the record I am really bad at quadratics, so don't hold back on how simple your steps are.

Thanks

2 Answers

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  • Rogue
    Lv 7
    8 years ago
    Favorite Answer

    via completing the square:

    2x^2+8x-30=x+3

    step on rearrange so as the 'x's are on one side and the constants are the other

    => 2x^2 + 7x = 33

    now that divide both sides by 2 to get the coefficient of the x^2 term to equal 1

    => x^2 + (7/2)x = 33/2

    now square half of the coefficient of the x^1 term and add it to both sides

    => x^2 + (7/2)x + (7/4)^2 = 33/2 + (7/4)^2

    you now have the pattern of x^2 + bx + (b/2)^2 = (x + b/2)^2

    => (x + 7/4)^2 = 313/16

    now take the square root of both sides

    => x + 7/4 = ±√(313)/4

    now isolate the x

    => x = (-7-√313)/4 or (√313 - 7)/4

  • Anonymous
    8 years ago

    ok i so i will find it for you

    there is one zero in 30 which is 0 and thats it!

    easy

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