Question

The range of the function f(k) = k2 + 2k + 1 is {25, 64}. What is the function’s domain?

{5, 8}



{-5, -8}



{3, 8}



{4, 7}



{4, 8}

Answer 1

answer is D {4,7}

if u put those values in the equation then u will get that output {25,64}

Answer 2

Correct option is:

{4,7}

Explanation:

The range of the function f(k) = k² + 2k + 1 is {25, 64}.

i.e. k²+2k+1 can take only two values either 25 or 64

When k=5 ,k²+2k+1=36

when k= -5 ,k²+2k+1=16

when k=8 ,k²+2k+1=81

Hence, domain set cannot contain the points 5,8 and -5

The only option that do not contain any of these numbers is:

{4,7}

Also when k=4 , k²+2k+1=25

and when k=7 , k²+2k+1=64

Hence, Correct option is:

{4,7}