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4t^{2}-8t-20=0
Quadratic polynomial can be factored using the transformation ax^{2}+bx+c=a\left(x-x_{1}\right)\left(x-x_{2}\right), where x_{1} and x_{2} are the solutions of the quadratic equation ax^{2}+bx+c=0.
t=\frac{-\left(-8\right)±\sqrt{\left(-8\right)^{2}-4\times 4\left(-20\right)}}{2\times 4}
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.
t=\frac{-\left(-8\right)±\sqrt{64-4\times 4\left(-20\right)}}{2\times 4}
Square -8.
t=\frac{-\left(-8\right)±\sqrt{64-16\left(-20\right)}}{2\times 4}
Multiply -4 times 4.
t=\frac{-\left(-8\right)±\sqrt{64+320}}{2\times 4}
Multiply -16 times -20.
t=\frac{-\left(-8\right)±\sqrt{384}}{2\times 4}
Add 64 to 320.
t=\frac{-\left(-8\right)±8\sqrt{6}}{2\times 4}
Take the square root of 384.
t=\frac{8±8\sqrt{6}}{2\times 4}
The opposite of -8 is 8.
t=\frac{8±8\sqrt{6}}{8}
Multiply 2 times 4.
t=\frac{8\sqrt{6}+8}{8}
Now solve the equation t=\frac{8±8\sqrt{6}}{8} when ± is plus. Add 8 to 8\sqrt{6}.
t=\sqrt{6}+1
Divide 8+8\sqrt{6} by 8.
t=\frac{8-8\sqrt{6}}{8}
Now solve the equation t=\frac{8±8\sqrt{6}}{8} when ± is minus. Subtract 8\sqrt{6} from 8.
t=1-\sqrt{6}
Divide 8-8\sqrt{6} by 8.
4t^{2}-8t-20=4\left(t-\left(\sqrt{6}+1\right)\right)\left(t-\left(1-\sqrt{6}\right)\right)
Factor the original expression using ax^{2}+bx+c=a\left(x-x_{1}\right)\left(x-x_{2}\right). Substitute 1+\sqrt{6} for x_{1} and 1-\sqrt{6} for x_{2}.
x ^ 2 -2x -5 = 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 4
r + s = 2 rs = -5
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 = 1 - u s = 1 + u
Two numbers r and s sum up to 2 exactly when the average of the two numbers is \frac{1}{2}*2 = 1. 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>
(1 - u) (1 + u) = -5
To solve for unknown quantity u, substitute these in the product equation rs = -5
1 - u^2 = -5
Simplify by expanding (a -b) (a + b) = a^2 – b^2
-u^2 = -5-1 = -6
Simplify the expression by subtracting 1 on both sides
u^2 = 6 u = \pm\sqrt{6} = \pm \sqrt{6}
Simplify the expression by multiplying -1 on both sides and take the square root to obtain the value of unknown variable u
r =1 - \sqrt{6} = -1.449 s = 1 + \sqrt{6} = 3.449
The factors r and s are the solutions to the quadratic equation. Substitute the value of u to compute the r and s.