Write the main sources and the diseases caused by the deficiency of vitamins A and C.
Step 1: Vitamin A:
- Sources: Carrots, milk, fish liver oil
- Deficiency Disease: Night blindness
Step 2: Vitamin C:
- Sources: Citrus fruits, green vegetables
- Deficiency Disease: Scurvy (bleeding gums, weakness)
(b) Order of the differential equation: $ 5x^3 \frac{d^3y}{dx^3} - 3\left(\frac{dy}{dx}\right)^2 + \left(\frac{d^2y}{dx^2}\right)^4 + y = 0 $