Question

Solve the equation for a.

K = 4a + 9ab

a = K(4 + 9b)
a = 4(K + 9b)
a = a equals StartFraction 4 plus 9 b Over K EndFraction equals h.
a = a equals StartFraction K Over 4 plus 9 b EndFraction equals h.

Answer 1

Start from K = 4a + 9ab. Factor a on the right:
K = a(4 + 9b).

If 4 + 9b ≠ 0, divide both sides by 4 + 9b:
a = K / (4 + 9b).

If 4 + 9b = 0 then 9b = −4:
- If also K = 0, any a is a solution (infinitely many).
- If K ≠ 0, there is no solution.