A store in Hampton bought a leather chair for $494.47 and marked it up 100% from the original cost. Later on, Sally purchased the leather chair and paid Hampton sales tax of 5.5%. How much, including tax, did she pay for the leather chair?

-2

7 - 9 = -2

reversed:

-2 + 9 = 7

(a) x intercepts: -6 and 2

you can obtain these by solving the equation 0=x^2 +4x-12 using your favorite quadratic formula. but it is easy to verify -6 and 2 indeed satisfy this equation.

(b) y intercept: -12

this is obtained by setting x=0: 0^2+4*0-12 = -12

(c) the minimum value is: -16 (this is the vertex)

you can get the vertex by rewriting the equation into the form:

there is no global or local maximum as the function goes to infinity, so only in the limit sense: +infinity.