First you must have the quadratic equal to zero. In order to do this you must subtract 7 to both sides
x^2 + 20x + (100 - 7) = 7 - 7
x^2 + 20x + 93 = 0
Now you must find two numbers who's sum equals 20 and their multiplication equal 93
Are there any? NO!
This means that you have to use the formula:
[tex]\frac{-b±\sqrt{b^{2} - 4ac} }{2a}[/tex]
In this case:
a = 1
b = 20
c = 93
[tex]\frac{-(20) plus/minus\sqrt{20^{2} - 4(1)(93)} }{2*1}[/tex]
[tex]\frac{-20 plus/minus\sqrt{400 - 372} }{2}[/tex]
[tex]\frac{-20 plus/minus\sqrt{28} }{2}[/tex]
^^^We must simplify √28
√28 = 2√7
so...
[tex]\frac{-20 plus/minus 2\sqrt{7} }{2}[/tex]
simplify further:
[tex]-10 plus/minus\sqrt{7[/tex]
-10 + √7
or
-10 - √7
***plus/minus = ±
Hope this helped!
~Just a girl in love with Shawn Mendes
