#### Answer

(a) shrink $f(x)$ horizontally by a factor of $\frac{1}{2}$ and shift down 1 unit
(b) stretch $f(x)$ horizontally by a factor of 2 and stretch vertically by a factor of 2

#### Work Step by Step

(a) We can obtain $f(2x)-1$ by shrinking $f(x)$ horizontally by a factor of $\frac{1}{2}$ and shifting the graph down 1 unit.
(b) We can obtain $2f(\frac{1}{2}x)$ by stretching $f(x)$ horizontally by a factor of 2 and stretching the graph vertically by a factor of 2.