Real Numbers
Class 9th Mathematics Part I MHB Solution
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
