Algebra
Calculus
Trigonometry
Matrix
Question
Factor the expression
x(x−9)(x+9)
Evaluate
x3−81x
Factor out x from the expression
x(x2−81)
Solution
More Steps
Evaluate
x2−81
Rewrite the expression in exponential form
x2−92
Use a2−b2=(a−b)(a+b) to factor the expression
(x−9)(x+9)
x(x−9)(x+9)
Show Solution
Find the roots
x1=−9,x2=0,x3=9
Evaluate
x3−81x
To find the roots of the expression,set the expression equal to 0
x3−81x=0
Factor the expression
x(x2−81)=0
Separate the equation into 2 possible cases
x=0x2−81=0
Solve the equation
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Evaluate
x2−81=0
Move the constant to the right-hand side and change its sign
x2=0+81
Removing 0 doesn't change the value,so remove it from the expression
x2=81
Take the root of both sides of the equation and remember to use both positive and negative roots
x=±81
Simplify the expression
More Steps
Evaluate
81
Write the number in exponential form with the base of 9
92
Reduce the index of the radical and exponent with 2
9
x=±9
Separate the equation into 2 possible cases
x=9x=−9
x=0x=9x=−9
Solution
x1=−9,x2=0,x3=9
Show Solution