Question

If m is a whole number less than 5, complete the table and by inspection of the table, find the solution of the equation 2m – 5 = – 1:

m
2m – 5

Answer 1

Since, m is a whole number which is less than 5, then solution of the equation is given by putting the value of m = 0, 1, 2, 3, 4, ...

Now, put m = 0, then

⇒ 2m – 5 = 2 × 0 – 5 = – 5

Put m = 1, then 2m – 5 = 2 × 1 – 5 = – 3

Put m = 2, then 2m – 5 = 2 × 2 – 5 = 4 – 5 = – 1

Put m = 3, then 2m – 5 = 2 × 3 – 5 = 6 – 5 = 1

Put m = 4, then 2m – 5 = 2 × 4 – 5 = 3

Hence table is 

m	0	1	2	3	4
2m – 5	– 5	– 3	– 1	1	3

And given equation is 2m – 5 = – 1

⇒ 2m = – 1 + 5   .....[Transposing – 5 to RHS]

⇒ 2m = 4

⇒ `(2m)/2 = 4/2`  ......[Dividing both sides by 2]

⇒ m = 2