A child presents with growth failure. Biochemical analysis shows normal Ca2+, normal PTH, reduced phosphate, and increased ALP. What is the diagnosis? 

Match the following:
In the following, \( [x] \) denotes the greatest integer less than or equal to \( x \). 
Choose the correct answer from the options given below:
For x < 0:
f(x) = ex + ax
For x ≥ 0:
f(x) = b(x - 1)2