Answer:
x = 11, -1
Step-by-step explanation:
First, let's identify what the quadratic formula is:
x = [-b ± √(b² - 4(a)(c))] / 2
Our equation is written in standard form:
ax² + bx + c = 0
x² - 10x - 11 = 0
Let's plug in what we know.
x = [-(-10) ± √((-10)² - 4(1)(-11))] / 2
Evaluate the exponent.
x = [-(-10) ± √(100 - 4(1)(-11))] / 2
Simplify the negatives.
x = [10 ± √(100 - 4(1)(-11))] / 2
Multiply.
x = [10 ± √(100 + 44)] / 2
Simplify the parentheses.
x = [10 ± √(144)] / 2
Simplify the radical (√)
x = [10 ± 12] / 2
Evaluate the ±.
x = [10 + 12] / 2
x = [22] / 2
x = 11
or
x = [10 - 12] / 2
x = [-2] / 2
x = -1
Your answers are x = 11, -1
Hope this helps!
