Questions: Find the real solutions of the following equation.
sqrt[15](x^2+2x)=-1
Transcript text: Find the real solutions of the following equation.
\[
\sqrt[15]{x^{2}+2 x}=-1
\]
Solution
Solution Steps
Step 1: Analyze the equation
The given equation is:
15x2+2x=−1
The 15th root of a real number is defined for all real numbers, and its output is always a real number. However, the 15th root of a real number is negative only if the radicand (the expression inside the root) is negative.
Step 2: Set up the equation for the radicand
Since the 15th root of x2+2x equals −1, we can write:
x2+2x=(−1)15
Simplify the right-hand side:
x2+2x=−1
Step 3: Rearrange the equation into standard quadratic form
Move all terms to one side to form a quadratic equation:
x2+2x+1=0
This simplifies to:
(x+1)2=0
Step 4: Solve the quadratic equation
Take the square root of both sides:
x+1=0
Solve for x:
x=−1
Step 5: Verify the solution
Substitute x=−1 back into the original equation to ensure it satisfies the equation:
15(−1)2+2(−1)=151−2=15−1=−1
The solution x=−1 is valid.