This question says use the quadratic
formula to solve for X. And we have 8x
squared plus 7x plus 1 equals 0
so I'm just going to rewrite that 8x
squared plus 7x plus 1 equals 0. So to
use the quadratic formula we have to
have the equation in the general form
which it already is:
a x squared plus BX plus C equals 0. So
in this case, a is equal to 8 B equals 7
and C equals 1. Note that if this was minus, so if it was 8x squared minus 7x, then b would be
called negative 7. Now we need to use the
quadratic formula, and the quadratic
formula is x equals negative b plus or
minus the square root of b squared minus
4ac all over 2a. So let's plug in x
equals negative B, which is negative 7,
plus or minus 7 squared (B squared) minus 4 times a, which is 8, times C, which is 1,
all over 2 times a which is 8. Continuing, x equals negative 7 plus or
minus square root 7 squared is 49 minus
4 times 8 times 1 - 4 times 8 is 32 so
it's 49 minus 32 or 17 all over 2 times
8 which is 16. Now we can split it up.
x equals negative 7 plus root 17 over 16, 
or x equals negative 7 minus square root
of 17 over 16.
In this case when you do the math using
the calculator x equals negative 0.18
rounding to the nearest hundredth, or you
doing the math using the calculator here, x equals negative 0.70
So these are the two possible
answers with the quadratic equation
which was shown here.
