Write, in the form y=cx+dax+b , the function that results when y=x1 is transformed by:
a. <b>a</b> a vertical dilation with scale factor 21
b. <b>b</b> a horizontal dilation with scale factor 3
c. <b>c</b> a horizontal translation of −3
d. <b>d</b> a vertical translation of 4.