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Math Challenge II-A 2.28

 
 
KiangZhi Feng Etan的头像
Math Challenge II-A 2.28
KiangZhi Feng Etan - 2020年06月14日 Sunday 18:21
 
Hello! May you please help me with problem 2.28 on this week's (June 10-17) assignment? I tried making the Vieta's Formulas and substituting them into each other, but it did not work. Please help me. Thank you!
 
ProfessorAreteem的头像
Re: Math Challenge II-A 2.28
ProfessorAreteem - 2020年06月16日 Tuesday 23:25
 

When you have a quadratic equation of the form $ax^2 + bx + c =0$, Vieta's formulas tell you that the roots, $x_1$ and $x_2$, are such that $x_1 + x_2 = \dfrac{-b}{a}$, and $x_1x_2 = \dfrac{c}{a}$.

Use these to rewrite $x_1^2 + x_2^2$ in terms of $a$, $b$, and $c$ only.