If x 0, then (4x + 9x)^2

Question

If  x > 0 , then  (\sqrt{4x} + \sqrt{9x})^2

A. 5x
B. 6x 
C. 13x
D. 25x
E. 30x

pratik3006 · Answer

^2= (√4x)^2 +(√9x)^2 +2*√4x*√9x
=4x+9x+2*√36x^2
=13x + 2*6x
=13x +12x
=25x

Hence, Option -D

Posted from my mobile device

KarishmaB · Answer

(\sqrt{4x} + \sqrt{9x})^2

Take sqrt(x) common to get:

\sqrt{x}^2 * (\sqrt{4} + \sqrt{9})^2

x * (2 + 3)^2

25x

Answer (D)

KrishnakumarKA1 · Answer

Hi,

Another way is quickly plugging-in the value of “x”.

Given x > 0,

x = 1(We can try any value, here answer choices are wide enough, so we can try “x” as “1” itself).

(√(4x)+ √(9x))^2 = (√(4)+ √(9))^2 = 5^2 = 25.

So, when substitute “x=1”, only answer choices we get, is answer choice D(25x).

Hence answer is D.

Archit3110 · Answer

upon solving eqn we would get 4x+9x+ 2 sq rt 36x^2
= 25x option D

If x > 0, then (4x + 9x)^2