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:
In this case:
a = 1
b = 20
c = 93
^^^We must simplify √28
√28 = 2√7
so...
simplify further:
-10 + √7
or
-10 - √7
***plus/minus = ±
Hope this helped!
~Just a girl in love with Shawn Mendes
