Question

calculati x1^2+x2^2 stiind ca x1 si x2 sunt sol. ecuatiei 2x^2-x-5=0
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Answer 1

[tex]2x^{2}-x-5=0 [/tex]
$x_1+x_2= \frac{-b}{a} =\frac{1}{2}$
$x_1x_2= \frac{c}{a} = \frac{-5}{2}$
$x_1^{2}+x_2^{2}=(x_1+x_2)^{2}-2x_1x_2= (\frac{1}{2}) ^{2}-2* \frac{-5}{2} = \frac{1}{4} +5= \frac{21}{4}$