Answer:
Step-by-step explanation:
1.
c+9=±8
either c=8-9=-1
c=-8-9=-17
so c=-1,-17
D
2.
8x^2-3=2
8x^2=5
so A
3.
so D
or
-1/3
its subtracting 1/3 every time
Area of triangle= Half of perpendicular times base
In short:1/2×p×b