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Let u and v be the solutions to 3x^2 + 5x + 7 = 0. Find u^2 + v^2.

 Feb 14, 2022
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So first we make the coefficient of x^2 = 1.

The new quadratic is: x2+53x+73=0

 

Then since we know by Vieta, the two solutions of the quadratic multiply to the c term, and they add to the b term * -1. The solutions are u and v.

Thus, u+v=53, and uv=73

 

Since u2+v2=(u+v)22uv, we can substitute in our previous values. 

Then u2+v2=259143.

 

Thus, u2+v2=179.

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 Feb 14, 2022

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