The 63 is the err in her explanation here.
Answer:
x-intercepts: (2,0), (4,0)
y-intercepts: (0,-8)
Explanation:
To find the x intercept(s), you must compute where y=0. So solve 0= -x^2 + 6x - 8. So, the x intercepts are: (2,0) and (4,0) since the solutions to the mentioned equation are x=2 and x=4. To find the y intercept(s) compute what is y when x=0. In this case, when x=0, y=-8. So the only y intercept is (0,-8).
Using Gauss's method
Total number of terms = [15-(-129)]/4+1=36+1=37
Add
S=15+11+7+....-125-129
S=-129-125-...+7+11+15
--------------------------------
2S=-114-114-114...(37 times)
=>
sum=S=(1/2)*(-114)*37=-2109
Using AP, T(n)=15+11+7+....-129
T(n)=19-4n => T(1)=15, T(37)=-129
S(n)=(1/2)(37)(T(1)+T(37)=(1/2)37(15-129)=2109