Posted by Matt on Monday, July 8, 2013 at 10:30pm.
Let y=f(x) be a function with domain=[7,8] and range=[12,9]. Find the range of the function y=f(2x)

Math  Steve, Tuesday, July 9, 2013 at 10:59am
Can't tell. If f(x) is linear, then just multiply the range by 2 to get [18,24]
For example, if f(x) = 7/5 x  11/5
then f(2x) = 22/5  14/5 x
and the range is indeed [18,24]
But, if f(x) is not linear, say
f(x) = 7/5 x^2  403/5 then
f(2x) = 806/5  28/5 x^2
and the range is now [986/5,566/5]