Practice Set 2.5 Real Numbers Class 9th Mathematics Part I MHB Solution

Real Numbers

Class 9th Mathematics Part I MHB Solution

Practice Set 2.5

Question 1.

Find the value.
(i) |15 - 2|
(ii) |4 - 9|
(iii) |7| × |-4|

Answer:

Absolute value describes the distance of a number on the number line from 0 without considering which direction from zero the number lies. The absolute value of a number is never negative.

Therefore,

i. |15 - 2| = |13| = 13

ii. |4 - 9| = |-5| = 5

iii. |7| × |-4| = 7 × 4 = 28

Question 2.

Solve.

i. |3x - 5| = 1

ii. |7 – 2x| = 5

iii. 

iv. 

Answer:

i. |3x - 5| = 1

⇒ 3x - 5 = 1 or 3x - 5 = -1

⇒ 3x = 1 + 5 or 3x = -1 + 5

⇒ 3x = 6 or 3x = 4

ii. |7 – 2x| = 5

⇒ 7 – 2x = 5 or 7 – 2x = -5

⇒ 2x = 7 - 5 or 2x = 7 + 5

⇒ 2x = 2 or 2x = 12

⇒ x = 1 or x = 6

iii. 

⇒ 8 – x = 2 × 5 or 8 – x = 2 × -5

⇒ 8 – x = 10 or 8 – x = -10

⇒ x = 8 – 10 or x = 8 + 10

⇒ x = -2 or x = 18

iv. 

⇒ 20 + x = 4 × 5 or 20 + x = 4 × -5

⇒ 20 + x = 20 or 20 + x = -20

⇒ x = 20 – 20 or x = -20 – 20

⇒ x = 0 or x = -40