Find, in the form y=ax2+bx+c , the quadratic function whose graph:
a. touches the x-axis at 3 and passes through (2, 2)
b. has x-intercepts 3 and −2 , and y-intercept 3
c. passes through (−1,−9) , (1,5) , and (2,15)
d. has vertex (3, 15) and passes through the point (1, 7).