Write the slope-intercept form when slope=-1 and the y-intercept= (0,-3)

Find the zero function by factoring (try to show work) h(x)=-x^2-6x-9

F(n + 1) = f(n) – 8. if f(1) = 100, what is f(6)?

Can someone factor this fully? my friend and i have two different answers and i would like to know if either of them is right. you in advance. a^2 - b^2 + 25 + 10a