25x^2-40x-81=0

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Solution for 25x^2-40x-81=0 equation:



25x^2-40x-81=0
a = 25; b = -40; c = -81;
Δ = b2-4ac
Δ = -402-4·25·(-81)
Δ = 9700
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:
$\sqrt{\Delta}=\sqrt{9700}=\sqrt{100*97}=\sqrt{100}*\sqrt{97}=10\sqrt{97}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-40)-10\sqrt{97}}{2*25}=\frac{40-10\sqrt{97}}{50} $
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-40)+10\sqrt{97}}{2*25}=\frac{40+10\sqrt{97}}{50} $

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