TN 11th, Maths Chapter 2, Exercise 2.2

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Class : XI
Subject : Maths
Chapter : 2
Exercise : 2.2


Que 1 :

Solve for " x

(i) |3-x| < 7

|x| < r
 -r < x < r

|3-x|<7
-7 < (3-x) < 7
-7-3 < -x < 7-3
-10 < -x < 4

∴ -4 < x < 10





(ii) |4x-5| ≥ -2

|x-a| ≥ r
(x-a) ≥ -r 

|4x-5| ≥ 2         
∵ r < 0
x ∈ R




(iii) |3-(3/4)x| ≤ 1/4

|3-(3/4)x| ≤ 1/4
3|1-(1/4)x| ≤ 1/4
|1-(1/4)x| ≤ 1/12
|(4-x)/4| ≤ 1/12
1/4|4-x)| ≤ 1/12
|4-x| ≤ (1/12)(4/1)
|4-x| ≤ 1/3
[-(x-4)] ≤ 1/3                     |x-a|≤ r
-1/3 ≤ x-4 ≤ 1/3                 -r ≤ x-a ≤ r
(-1/3)+(4) ≤ x ≤ (1/3)+(4)

11/3 ≤ x ≤ 13/3





(iv) |x|-10 < -3

|x|<7
-r < x < r

|x|-10 < -3
     |x| < -3+10
     |x| < 7

-7 < x < 7   





Que 2 :

Solve (1/|2x-1|) < 6 and express the solution using the interval notation.

Solution :

(1/|2x-1|) < 6                  |x|> r
|2x-1| < 1/6                    x<r; x<r
-1/6> 2x-1 > 1/6               x ∈ (-∞,-r) ⋃ (r,∞)
(-1/6)+1 > 2x-1 > (1/6)+1
5/6 > 2x > 7/6
5/12 > x > 7/12
x ∈ (-∞, 5/12] ∪ [7/12,∞)

←-∞ –––––|––––––|––––– ∞→
                     (5/12)                (7/12)






Que 3 :

Solve -3|x|+5 ≤ -2 and graph solution set in an number line.

Solution :

-3|x|+5 ≤-2
    -3|x| ≤ -2-5
    -3|x| ≤ -7                       |x| ≤ r
       |x| ≤ 7/3                     -r < x < r
 -7/3 ≤ x ≤ 7/3                  x ∈ (-∞,-r]⋃[∞,r)
x ∈ (-∞,7/3] ⋃ [7/3,∞)

←-∞ –––––]––––––|––––––[––––– ∞→
                     -7/3              0              7/3






Que 4 :

Solve 2|x+1|-6≤7 & the graph of solution set in an Number line.

Solution :

2|x+1|-6 ≤ 7
    2|x+1|≤ 7+6
    2|x+1|≤ 13
      |x+1| ≤ 13/2 
    |x-(-1)|≤ 13/2                  |x|≤r
-13/2 ≤ x+1 ≤ 13/2             -r < x < r
-15/2 ≤ x ≤ 11/2

←-∞ –––––|––––––|––––––|––––– ∞→
                    -15/2                      0                    11/2






Que 5 :

Solve 1/5|10x - 2| < 1

Solution :

1/5|10x-2| < 1
|10x - 2| < 1(5/1)
10x - 2< 5 or 10x - 2 > -5

If 5 is Positive       If 5 is negative
10x < 5+2             10x > -5+2
10x < 7                  10x > -3
    x < 7/10                 x > -3/10

-3/10 < x < 7/10

←-∞ –––––|––––––|––––––|––––– ∞→
                      -3/10                    0               7/10






Que 6 :

Solve |5x – 12| < -2

Solution :

|5x - 12| < -2
5 |x - 12/5| < -2
|x-12/5| < -2/5
-(-2/5) < (x-12/5) < (-2/5)
2/5 < (x -12/5) < -(2/5)
(2/5)+(12/5) < x < (-2/5)+(12/5)
14/5 < x < 10/5
This Is Impossible,
So, it Has no solution.




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