Question

If g(x) = sqrt(x-3) and k(x) = x^2 + 5 then determine: (g*k)(7)

Answer 1

just multiply the two functions and evaluate at x=7

Answer 2

How do you multiply them?

Answer 3

(x-3) * (x^4 + 25). Is this what you are suppose to get when you multiply them?\[x ^{5}-3x ^{4}+25x-75\]

Answer 4

you forgot the square root over the x-3

Answer 5

(g*k)(7) is the same as g(7) * k(7)

Answer 6

I squared the both equations so I can get rid of the square root.

Answer 7

find g(7) and k(7). Then multiply those results

Answer 8

squaring x^2 + 5 does not give x^4 + 25

also, squaring can only be done when you square both sides of an equation

Answer 9

Would the answer be 216 then?

Answer 10

Oh I keep forgetting some steps. But I got the answer doing what you said.

Answer 11

it's not 216

Answer 12

x^2 + 5 = 7^2 + 5 = 49 + 5 = 54
sqrt(x - 3) = sqrt(7 - 3) = sqrt(4) = 2
54 * 2 = 108
I forgot to sqrt the 4 earlier.

Answer 13

108 is correct

Answer 14

Thanks!

Answer 15

no problem