Distributive property. -6 x a plus -8 x 8 = -6a -48
Your answer would be the last option, c = √(E/m).
We can see this when we rearrange the equation, as:
E = mc²
÷ m
E/m = c²
√
√(E/m) = c
So you got all the steps in rearranging correct :)
I hope this helps!
Plug in -3 for x
f(-3) = 2(-3) - (-3 + 6)
f(-3) = -6 - (3)
f(-3) = -9
Solution: f(-3) = -9