Solve Using the Quadratic Formula x^2-81=0

Problem

x2−81=0

Solution

1. Identify the coefficients for the quadratic equation in the form a*x2+b*x+c=0

a=1

b=0

c=−81

2. Substitute these values into the quadratic formula.

x=(−b±√(,b2−4*a*c))/(2*a)

x=(−0±√(,0−4*(1)*(−81)))/(2*(1))

3. Simplify the expression inside the square root (the discriminant).

x=(±√(,0+324))/2

x=(±√(,324))/2

4. Evaluate the square root and solve for x

x=(±18)/2

x=±9

Final Answer

x=9,−9

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