Quandaries
and Queries
Jim
Student
Secondary Level Questions
I just want to check a couple average rate of change problems because i just guessed on how to do them. Can you tell me how to do them?
the question says if f(x) = sqrt(x + 3), find f( x + rx). I got sqrt( x + rx + 3)
the other two are : f(x)= 3x-1 (f(x) - f(1)) / (x-1) ... I GOT 3 &
f(x)= x3 - x (f(x) - f(1)) / (x-1) ... I GOT x2 + x
Hi Jim,
I got the same answer as you for all three problems.
I can show you what I did in the second and third problems.
If f(x) = 3x - 1 then
f(x) - f(1) = (3x - 1) - (3 - 1) = 3x - 3 = 3(x - 1)
and hence
f(x) - f(1)/x - 1 = 3(x - 1)/x - 1 = 3
If f(x) = x3 - x then
f(x) - f(1) = (x3 - x) - (1 - 1) = x3 - x = x(x2 - 1) = x(x - 1)(x + 1)
and hence
f(x) - f(1)/x - 1 = x(x - 1)(x + 1/x - 1 = x(x + 1)
Penny