We'll subtract 3x + 40 both
sides:
x^2 - 3x-40 = 0
We'll
apply quadratic formula:
x1 =
[-b+sqrt(b^2-4ac)]/2a
x2 =
[-b-sqrt(b^2-4ac)]/2a
We'll identify
a,b,c:
a=1
b=-3
c=-40
We'll
calculate delta:
delta =
b^2-4ac
delta = 9+160
delta =
169
Since delta is positive, we'll have 2 distinct real
roots of the equation x^2 - 3x-40 =
0.
x1=[3+sqrt(9+160)]/2
x1 =
(3+13)/2
x1 = 8
x2
= -5
The real roots are: {-5 ;
8}.
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