Find the rule of the mapping: x 0 3 6 9 12 y -2 4 10 16 22

Correct Answer is : y⟶2x−2y 2x - 2y⟶2x−2

Correct Answer is : y⟶2x−2y 2x - 2y⟶2x−2

Test Index

BECE Mathematics 2018 Paper

Question : 35

Total: 40

Solution:

Concept:

A mapping rule can be identified by observing how

y

changes as

x

changes in the table.

Explanation:

When

x

increases by

3

y

increases by

6

So the rate of change is

\frac{6}{3} = 2

This suggests a linear rule of the form

y = 2x + c

Use

x = 0

and

y = -2

-2 = 2(0) + c

, so

c = -2

Thus, the rule is

y \longrightarrow 2x - 2

Check

x = 3

2(3) - 2 = 6 - 2 = 4

Check

x = 12

2(12) - 2 = 24 - 2 = 22

The rule works for every value in the table.

Answer:

y \longrightarrow 2x - 2

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