Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

Find the value of x2 - 7 if

\(\sqrt {5x + 16}\) + \(\sqrt {5x - 16}\) = \(\sqrt {41}\) + \(\sqrt {9}\).

Options:

15

18

32

35

Correct Answer:

18

Explanation:

We can easily see that x = 5 will satisfy the expression:

⇒ \(\sqrt {5x + 16}\) + \(\sqrt {5x - 16}\) = \(\sqrt {41}\) + \(\sqrt {9}\)

⇒ \(\sqrt {25 + 16}\) + \(\sqrt {25 - 16}\) = \(\sqrt {41}\) + \(\sqrt {9}\)

⇒ \(\sqrt {41}\) + \(\sqrt {9}\) = \(\sqrt {41}\) + \(\sqrt {9}\)

Hence,

x2 - 7 = 52 - 7 = 25 - 7 = 18