Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If (3p - 5m) = 5 and pm = 6, then what is the value of $(9p^2 - 25m^2)$ ?

Options:

$±5\sqrt{385}$

$30\sqrt{10}$

$5\sqrt{385}$

$±30\sqrt{10}$

Correct Answer:

$±5\sqrt{385}$

Explanation:

Given =

(3p - 5m) = 5

pm = 6

We know that,

 (a - b)2 = a2 + b2 - 2ab

(a2 - b2) = (a - b)(a + b)

(a + b)2 = (a - b)2 + 4ab

Calculation:

= (3p + 5m)2 = (3p - 5m)2 + 4 × 3p × 5m

= 25 + 60 × 6

= (3p + 5m) = ±\(\sqrt {385}\)