x^2+9x+20=0
Solve using quadratic formula
You must know the quadratic formula to the point when somebody wakes you
at 3:00 am and says "What is the quadratic formula?", you must be able to
recite it , and go back to sleep in 20 seconds.
x^2+9x+20=0
x = (-9 ± √(81-4(1)(20))/2
= (-9 ± √1)/2
= ....
Hey, that factored! How do I know that?
To solve the quadratic equation using the quadratic formula, you need to plug the coefficients of the variables into the formula and simplify the equation.
The quadratic formula is given by:
x = (-b ± √(b^2 - 4ac)) / (2a)
Here, the quadratic equation is:
x^2 + 9x + 20 = 0
Comparing this equation to the standard form (ax^2 + bx + c = 0), we have:
a = 1, b = 9, and c = 20
Now, substituting these values into the quadratic formula, we get:
x = (-(9) ± √((9)^2 - 4(1)(20))) / (2(1))
Simplifying further:
x = (-9 ± √(81 - 80)) / 2
x = (-9 ± √1) / 2
We have two solutions:
x = (-9 + 1) / 2 = -8 / 2 = -4
x = (-9 - 1) / 2 = -10 / 2 = -5
Therefore, the solutions to the quadratic equation x^2 + 9x + 20 = 0 are x = -4 and x = -5.