jwamala wrote:

If \(g(x) = 3x + \sqrt {x}\), what is the value of \(g(d^2 +6d+9)\)?

(Chapter 5, Page 79 - In Action problem #2)

SEO was poor for this question. Also, this is more open ended practice so it's less GMAT like.

Hi,

1)\(g(x) = 3x + \sqrt {x}\)..

and \(g(d^2 +6d+9)\)..

so substitute x as d^2 +6d+9..

\(g(d^2 +6d+9) = 3(d^2 +6d+9) + \sqrt {d^2 +6d+9}\)..

\(3d^2+18d+27+d+3=3d^2+19d+30\)

or

2)\(3x + \sqrt {x}=\sqrt {x}(3\sqrt {x}+1)\)...

if\(x= d^2 +6d+9\), \(\sqrt{x}\)=\(\sqrt{(d+3)^2}\)..

\(\sqrt {x}(3\sqrt {x}+1)\)=\(\sqrt{(d+3)^2}(3\sqrt{(d+3)^2}+1)\)..

\(\sqrt{(d+3)^2}(3\sqrt{(d+3)^2}+1)\)...

=\((d+3)(3d+9+1)=(d+3)(3d+10)\)

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1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372

2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html

3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html

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