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Let f(x)=x2f(x) = x^2 and g(x)=2xg(x) = 2^x, for all real xx. Then the value of f(f(g(x))+g(f(x)))f(f(g(x)) + g(f(x))) at x=1x = 1 is

Solution

✅ Correct Option: 3

Given: f(x)=x2f(x) = x^2 and g(x)=2xg(x) = 2^x

We need to find f(f(g(x))+g(f(x)))f(f(g(x)) + g(f(x))) at x=1x = 1

CRITICAL: Notice the parentheses! We need f(something)f(\text{something}) where "something" =f(g(x))+g(f(x))= f(g(x)) + g(f(x))


Find g(1)g(1):

g(1)=21=2g(1) = 2^1 = 2


Find f(g(1))=f(2)f(g(1)) = f(2):

f(2)=22=4f(2) = 2^2 = 4


Find f(1)f(1):

f(1)=12=1f(1) = 1^2 = 1


Find g(f(1))=g(1)g(f(1)) = g(1):

Since f(1)=1f(1) = 1, we need g(1)=21=2g(1) = 2^1 = 2


Calculate f(g(1))+g(f(1))f(g(1)) + g(f(1)):

f(g(1))+g(f(1))=4+2=6f(g(1)) + g(f(1)) = 4 + 2 = 6


Apply function ff to this result:

f(f(g(1))+g(f(1)))=f(6)=62=36f(f(g(1)) + g(f(1))) = f(6) = 6^2 = 36

Memory Trick: First find what's inside the outer f(here)f(\text{here}), then apply ff to that result

Answer: 3636

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