Consider the equation 4√2x3 − 3√2x −1 = 0 .
Statement 1: Solution of this equation is cos(π/12) .
Statement 2: This equation has only one real solution.
Correct Answer :
Statement 1 is true but statement 2 is false
Solution :
To analyze the given statements, we start with the cubic equation:
First, we can divide the entire equation by (since ):
This can be rewritten as:
Recall the trigonometric triple-angle identity for cosine:
Let us substitute into our equation, where we restrict to find unique real roots:
Since , the angle lies in the interval . Within this interval, we solve for where the cosine value is :
1)
2)
3)
Each of these three values of lies in the range and yields a distinct value for :
Thus, we have three distinct real solutions. Let us evaluate the statements:
Statement 1: "Solution of this equation is cos(π/12)". Since is indeed a root of the equation, Statement 1 is true.
Statement 2: "This equation has only one real solution". Since we found three distinct real solutions, Statement 2 is false.
Therefore, Statement 1 is true but Statement 2 is false.
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