Use pythagoras
d = √(Δx² + Δy²)
d = √(12-2)² + (9-4)²
d = √(10² + 5²)
d = √(100 + 25)
d = √125
d = 5√5
d = 5 × 2.236
d = 11.18
The nearest tenth is 11.2, so the distance is near to 11.2
That means the average of all data point equal:
(99+122+103+113+109+x)/6 = 103
===> (546+x)/6 = 103===> 546+x=618 & x=618-546=72, so x =72
F(x) = 3(x-4)^2-38 because finding the perfect square would get you f(x)+38=3(x^2-8x+16) and then finding the squareroot of that and moving the constant on the left back to the right would leave u with f(x)=3(x-4)^2-38