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Question 140. In the equation 2x^2 - 3x + 4 = 0, what is the sum of the squares of the roots?

Question 140 In The Equation 2x2 3x 4 0 What Is The Sum Of The Squares Of The Roots class=

Sagot :

Given the quadratic equation:

[tex]2x^2-3x+4=0[/tex]

We solve this equation to find the roots. The general solution for a quadratic equation is given by the expression:

[tex]x=\frac{-b\pm\sqrt[]{b^2-4\cdot a\cdot c}}{2a}[/tex]

Looking at the equation, we identify:

[tex]\begin{gathered} a=2 \\ b=-3 \\ c=4 \end{gathered}[/tex]

Then, using the general solution formula:

[tex]\begin{gathered} x=\frac{-(-3)\pm\sqrt[]{3^2-4\cdot2\cdot4}}{2\cdot2}=\frac{3\pm\sqrt[]{9-32}}{4} \\ \Rightarrow x_1=\frac{3+\sqrt[]{23}i}{4} \\ \Rightarrow x_2=\frac{3-\sqrt[]{23}i}{4} \end{gathered}[/tex]

Now, we need to know the sum of the squares of x₁ and x₂. Then:

[tex]\begin{gathered} x^2_1+x^2_2=\frac{1}{16}(9+2\cdot\sqrt[]{23}\cdot i-23+9-2\cdot\sqrt[]{23}\cdot i-23) \\ \Rightarrow=\frac{1}{16}(18-46)=-\frac{28}{16}=-\frac{7}{4} \end{gathered}[/tex]