Solve for x (complex solution)
x=\frac{-1+\sqrt{47}i}{4}\approx -0.25+1.71391365i
x=\frac{-\sqrt{47}i-1}{4}\approx -0.25-1.71391365i
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2x^{2}+x+6=0
All equations of the form ax^{2}+bx+c=0 can be solved using the quadratic formula: \frac{-b±\sqrt{b^{2}-4ac}}{2a}. The quadratic formula gives two solutions, one when ± is addition and one when it is subtraction.
x=\frac{-1±\sqrt{1^{2}-4\times 2\times 6}}{2\times 2}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 2 for a, 1 for b, and 6 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-1±\sqrt{1-4\times 2\times 6}}{2\times 2}
Square 1.
x=\frac{-1±\sqrt{1-8\times 6}}{2\times 2}
Multiply -4 times 2.
x=\frac{-1±\sqrt{1-48}}{2\times 2}
Multiply -8 times 6.
x=\frac{-1±\sqrt{-47}}{2\times 2}
Add 1 to -48.
x=\frac{-1±\sqrt{47}i}{2\times 2}
Take the square root of -47.
x=\frac{-1±\sqrt{47}i}{4}
Multiply 2 times 2.
x=\frac{-1+\sqrt{47}i}{4}
Now solve the equation x=\frac{-1±\sqrt{47}i}{4} when ± is plus. Add -1 to i\sqrt{47}.
x=\frac{-\sqrt{47}i-1}{4}
Now solve the equation x=\frac{-1±\sqrt{47}i}{4} when ± is minus. Subtract i\sqrt{47} from -1.
x=\frac{-1+\sqrt{47}i}{4} x=\frac{-\sqrt{47}i-1}{4}
The equation is now solved.
2x^{2}+x+6=0
Quadratic equations such as this one can be solved by completing the square. In order to complete the square, the equation must first be in the form x^{2}+bx=c.
2x^{2}+x+6-6=-6
Subtract 6 from both sides of the equation.
2x^{2}+x=-6
Subtracting 6 from itself leaves 0.
\frac{2x^{2}+x}{2}=-\frac{6}{2}
Divide both sides by 2.
x^{2}+\frac{1}{2}x=-\frac{6}{2}
Dividing by 2 undoes the multiplication by 2.
x^{2}+\frac{1}{2}x=-3
Divide -6 by 2.
x^{2}+\frac{1}{2}x+\left(\frac{1}{4}\right)^{2}=-3+\left(\frac{1}{4}\right)^{2}
Divide \frac{1}{2}, the coefficient of the x term, by 2 to get \frac{1}{4}. Then add the square of \frac{1}{4} to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}+\frac{1}{2}x+\frac{1}{16}=-3+\frac{1}{16}
Square \frac{1}{4} by squaring both the numerator and the denominator of the fraction.
x^{2}+\frac{1}{2}x+\frac{1}{16}=-\frac{47}{16}
Add -3 to \frac{1}{16}.
\left(x+\frac{1}{4}\right)^{2}=-\frac{47}{16}
Factor x^{2}+\frac{1}{2}x+\frac{1}{16}. In general, when x^{2}+bx+c is a perfect square, it can always be factored as \left(x+\frac{b}{2}\right)^{2}.
\sqrt{\left(x+\frac{1}{4}\right)^{2}}=\sqrt{-\frac{47}{16}}
Take the square root of both sides of the equation.
x+\frac{1}{4}=\frac{\sqrt{47}i}{4} x+\frac{1}{4}=-\frac{\sqrt{47}i}{4}
Simplify.
x=\frac{-1+\sqrt{47}i}{4} x=\frac{-\sqrt{47}i-1}{4}
Subtract \frac{1}{4} from both sides of the equation.
x ^ 2 +\frac{1}{2}x +3 = 0
Quadratic equations such as this one can be solved by a new direct factoring method that does not require guess work. To use the direct factoring method, the equation must be in the form x^2+Bx+C=0.This is achieved by dividing both sides of the equation by 2
r + s = -\frac{1}{2} rs = 3
Let r and s be the factors for the quadratic equation such that x^2+Bx+C=(x−r)(x−s) where sum of factors (r+s)=−B and the product of factors rs = C
r = -\frac{1}{4} - u s = -\frac{1}{4} + u
Two numbers r and s sum up to -\frac{1}{2} exactly when the average of the two numbers is \frac{1}{2}*-\frac{1}{2} = -\frac{1}{4}. You can also see that the midpoint of r and s corresponds to the axis of symmetry of the parabola represented by the quadratic equation y=x^2+Bx+C. The values of r and s are equidistant from the center by an unknown quantity u. Express r and s with respect to variable u. <div style='padding: 8px'><img src='https://opalmath.azureedge.net/customsolver/quadraticgraph.png' style='width: 100%;max-width: 700px' /></div>
(-\frac{1}{4} - u) (-\frac{1}{4} + u) = 3
To solve for unknown quantity u, substitute these in the product equation rs = 3
\frac{1}{16} - u^2 = 3
Simplify by expanding (a -b) (a + b) = a^2 – b^2
-u^2 = 3-\frac{1}{16} = \frac{47}{16}
Simplify the expression by subtracting \frac{1}{16} on both sides
u^2 = -\frac{47}{16} u = \pm\sqrt{-\frac{47}{16}} = \pm \frac{\sqrt{47}}{4}i
Simplify the expression by multiplying -1 on both sides and take the square root to obtain the value of unknown variable u
r =-\frac{1}{4} - \frac{\sqrt{47}}{4}i = -0.250 - 1.714i s = -\frac{1}{4} + \frac{\sqrt{47}}{4}i = -0.250 + 1.714i
The factors r and s are the solutions to the quadratic equation. Substitute the value of u to compute the r and s.
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Simultaneous equation
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\frac { d } { d x } \frac { ( 3 x ^ { 2 } - 2 ) } { ( x - 5 ) }
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Limits
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