Answer:
a = - 6, b = 13
Step-by-step explanation:
Given f(1) = 7 , that is f(x) = 7 when x = 1
f(3) = - 5 , that is f(x) = - 5 when x = 3
Substitute these values into f(x) = ax + b
a + b = 7 → (1)
3a + b = - 5 → (2)
Subtract (1) from (2) term by term to eliminate b
(3a - a) + (b - b) = - 5 - 7
2a = - 12 ( divide both sides by 2 )
a = - 6
Substitute a = - 6 into either of the 2 equations and solve for b
Substituting into (1)
- 6 + b = 7 ( add 6 to both sides )
b = 13
