Question

Consider the equations shown: ax + by = ab & 2ax + 3by = 3b Which of these is the value of y in terms of a? Option 1 : y = 3a – 35 Option 2 : y = 2ab – 3b Option 3 : y = 9a – 35 Option 4: y = 3 – 2a

Answer 1

Option 4: y = 3 – 2a

Explanation:

Given the simultaneous equation;

ax + by = ab ......... 1

2ax + 3by = 3b .....2

Required

Express y in terms of a

Using elimination method to eliminate x variable.

eqn 1 * 2 and eqn 2 *1 will give;

2ax + 2by = 2ab

2ax + 3by = 3b

Subtract

2by - 3by = 2ab - 3b

-by = 2ab - 3b

-by = b(2a-3)

-y = 2a-3

multiply through by -1

y = -2a + 3

y = 3-2a

Hence the value of y in terms of a is y = 3-2a