How does the graph of f(x) = log_2(x - 5) - 2f(x)=log2(x5)2 compare to its parent function f(x) = log_2 xlog2x?

1 Answer
Sep 7, 2015

log_2(x-5)-2log2(x5)2 is log_2(x)log2(x) shifted down 22 units, and shifted right 55 units.

Explanation:

For any function f(x)f(x):

f(x) + kf(x)+k is f(x)f(x) shifted up by kk units.

f(x) - kf(x)k is f(x)f(x) shifted down by kk units.

f(x+k) f(x+k) is f(x)f(x) shifted left by kk units.

f(x-k) f(xk) is f(x)f(x) shifted right by kk units.

From this we can quickly see that log_2(x-5)-2log2(x5)2 is log_2(x)log2(x) shifted down 22 units, and shifted right 55 units.

Desmos Graphing Calculator