Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If x2 - 5x + 25 = 0

Find the value of x5 - 5x4 - 3102

Options:

25

25\(\sqrt {2}\)

25\(\sqrt {3}\)

23

Correct Answer:

23

Explanation:

Formula → (a3 + b3) = (a + b) (a2 + b2 - ab)

x3 + 53 = (x + 5) (x2 - 5x + 25)

x3 + 53 = (x + 5) (0)

x3 = - 53

Now → x5 - 5x4 - 3102

⇒ x3 (x2 - 5x) - 3102

⇒ (-125) (-25) - 3102               (x2 - 5x +25 = 0⇒  x2 - 5x = -25)... (given)

= 3125 - 3102 = 23