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The solutions to \[2x^2 - 10x + 13 = 0\]are $a+bi$ and $a-bi,$ where $a$ and $b$ are positive. What is $a\cdot b?$[tex]The solutions to\[2x^2 - 10x + 13 = 0\]are $a+bi$ and $a-bi,$ where $a$ and $b$ are positive. What is $a\cdot b?$[/tex]

Respuesta :

Answer:  5/4

In decimal form, this is equivalent to 1.25

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Work Shown:

The given equation 2x^2-10x+13 = 0 matches the form ax^2+bx+c = 0

We see that a = 2, b = -10, c = 13. Plug those values into the quadratic formula to solve for x.

[tex]x = \frac{-b\pm\sqrt{b^2-4ac}}{2a}\\\\x = \frac{-(-10)\pm\sqrt{(-10)^2-4(2)(13)}}{2(2)}\\\\x = \frac{10\pm\sqrt{-4}}{4}\\\\x = \frac{10\pm2i}{4}\\\\x = \frac{2(5\pm i)}{2*2}\\\\x = \frac{5\pm i}{2}\\\\x = \frac{5}{2} \pm \frac{1}{2}i\\\\x = \frac{5}{2} + \frac{1}{2}i \ \text{ or } \ x = \frac{5}{2} - \frac{1}{2}i\\\\[/tex]

The two solutions are in the form [tex]a \pm bi[/tex] where a = 5/2 and b = 1/2

Therefore a*b = (5/2)*(1/2) = 5/4 = 1.25