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12.99x-16.1x^2=2.8125x^2
We move all terms to the left:
12.99x-16.1x^2-(2.8125x^2)=0
We get rid of parentheses
-16.1x^2-2.8125x^2+12.99x=0
We add all the numbers together, and all the variables
-18.9125x^2+12.99x=0
a = -18.9125; b = 12.99; c = 0;
Δ = b2-4ac
Δ = 12.992-4·(-18.9125)·0
Δ = 168.7401
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}$$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(12.99)-\sqrt{168.7401}}{2*-18.9125}=\frac{-12.99-\sqrt{168.7401}}{-37.825} $$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(12.99)+\sqrt{168.7401}}{2*-18.9125}=\frac{-12.99+\sqrt{168.7401}}{-37.825} $
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