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a+b=-9 ab=1\times 14=14
Factor the expression by grouping. First, the expression needs to be rewritten as m^{2}+am+bm+14. To find a and b, set up a system to be solved.
-1,-14 -2,-7
Since ab is positive, a and b have the same sign. Since a+b is negative, a and b are both negative. List all such integer pairs that give product 14.
-1-14=-15 -2-7=-9
Calculate the sum for each pair.
a=-7 b=-2
The solution is the pair that gives sum -9.
\left(m^{2}-7m\right)+\left(-2m+14\right)
Rewrite m^{2}-9m+14 as \left(m^{2}-7m\right)+\left(-2m+14\right).
m\left(m-7\right)-2\left(m-7\right)
Factor out m in the first and -2 in the second group.
\left(m-7\right)\left(m-2\right)
Factor out common term m-7 by using distributive property.
m^{2}-9m+14=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.
m=\frac{-\left(-9\right)±\sqrt{\left(-9\right)^{2}-4\times 14}}{2}
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.
m=\frac{-\left(-9\right)±\sqrt{81-4\times 14}}{2}
Square -9.
m=\frac{-\left(-9\right)±\sqrt{81-56}}{2}
Multiply -4 times 14.
m=\frac{-\left(-9\right)±\sqrt{25}}{2}
Add 81 to -56.
m=\frac{-\left(-9\right)±5}{2}
Take the square root of 25.
m=\frac{9±5}{2}
The opposite of -9 is 9.
m=\frac{14}{2}
Now solve the equation m=\frac{9±5}{2} when ± is plus. Add 9 to 5.
m=7
Divide 14 by 2.
m=\frac{4}{2}
Now solve the equation m=\frac{9±5}{2} when ± is minus. Subtract 5 from 9.
m=2
Divide 4 by 2.
m^{2}-9m+14=\left(m-7\right)\left(m-2\right)
Factor the original expression using ax^{2}+bx+c=a\left(x-x_{1}\right)\left(x-x_{2}\right). Substitute 7 for x_{1} and 2 for x_{2}.
x ^ 2 -9x +14 = 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.
r + s = 9 rs = 14
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{9}{2} - u s = \frac{9}{2} + u
Two numbers r and s sum up to 9 exactly when the average of the two numbers is \frac{1}{2}*9 = \frac{9}{2}. 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{9}{2} - u) (\frac{9}{2} + u) = 14
To solve for unknown quantity u, substitute these in the product equation rs = 14
\frac{81}{4} - u^2 = 14
Simplify by expanding (a -b) (a + b) = a^2 – b^2
-u^2 = 14-\frac{81}{4} = -\frac{25}{4}
Simplify the expression by subtracting \frac{81}{4} on both sides
u^2 = \frac{25}{4} u = \pm\sqrt{\frac{25}{4}} = \pm \frac{5}{2}
Simplify the expression by multiplying -1 on both sides and take the square root to obtain the value of unknown variable u
r =\frac{9}{2} - \frac{5}{2} = 2 s = \frac{9}{2} + \frac{5}{2} = 7
The factors r and s are the solutions to the quadratic equation. Substitute the value of u to compute the r and s.