Ira S. answered • 12/11/14

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A quadratic equation works like this.

x

^{2}+8x-20=0(x+10)(x-2)=0

x+10=0 or x-2=0

x=-10 or x=2

So when you are given the zeroes, just work backwards. For example if your zeroes, or roots, are 5 and -3, that means

x=5 or x = -3 which comes from

x-5=0 or x+3=0 which comes from

(x-5)(x+3)=0 which multiplied out, which is what I think you're refering to when you say the box method, is

x

^{2}-2x-15=0The same thing happens in a cubic equation or any other power for that matter.

your zeroes are -2, 3, -5 which means

x+2=0, x-3=0, or x+5=0 which comes from

(x+2)(x-3)(x+5)=0 so multiply that out to get

(x

^{2}-x-6)(x+5)=0 which equalsx

^{3}+4x^{2}-11x-30=0Again, I'm not sure what the box method is but your final answeer should match up with mine.

Hope this helped.