If f(x) = √x and g(x) = 7x + b, then
f(g(x)) = f(7x + b) = √(7x + b)
If the plot of f(g(x)) passes through (4, 6), then
f(g(4)) = √(7•4 + b) = √(28 + b) = 6
Solve for b :
√(28 + b) = 6
(√(28 + b))² = 6²
28 + b = 36
b = 36 - 28
b = 8
