kasih tau donk guys... pleaseeee

1.a. x=0
f(0)=0²-4.0-5=0-0-5=0-5=-5
(0,-5)
b. y=0
x²-4x-5=0
(x-5)(x+1)=0
x=5 atau x=-1
(5,0)&(-1,0)
C. x²-4x-5
a=1
b=-4
c=-5
D=b²-4ac=(-4)²-4(1)(-5)
=16+20=36
x=-b/2a=-(-4)/2.1=4/2=2
y=-D/4a=-36/4.1=-36/4=-9 atau
f(-b/2a) =f(2)=2²-4.2-5=4-8-5=-9
Koordinat titik puncak (2,-9)