Q 1 :

If |x+3|+xx+2>1, then x

  • (-5,-2)

     

  • (-1,)

     

  • (-5,-2)(-1,)

     

  • none of these

     

(3)

We have,  |x+3|+xx+2>1

 |x+3|+xx+2-1>0|x+3|-2x+2>0

Now, two cases arise:

Case I: Whenx+30, i.e., x-3.

Then,  |x+3|-2x+2>0x+3-2x+2>0x+1x+2>0

 {x+1>0 and x+2>0} or {x+1<0 and x+2<0}

 {x>-1 and x>-2} or {x<-1 and x<-2}

 x>-1 or x<-2

 x(-1,) or x(-,-2)

 x[-3,-2)(-1,)    [Since x-3]         ...(i)

Case II: When x+3<0, i.e., x<-3.

Then,  |x+3|-2x+2>0-x-3-2x+2>0

-(x+5)x+2>0x+5x+2<0

 {x+5<0 and x+2>0} or {x+5>0 and x+2<0}

 {x<-5 and x>-2}  which is not possible,

       or {x>-5 and x<-2}

 x(-5,-2)

 x(-5,-3)    [Since x<-3]                  ...(ii)

Combining (i) and (ii), the required solution is

x(-5,-2)(-1,)



Q 2 :

Solution of |3x+2|<1 is

  • [-1,-13]

     

  • {-13,-1}

     

  • (-1,-13)

     

  • None of these

     

(3)

We have,  

|3x+2|<1-1<3x+2<1-3<3x<-1-1<x<-13



Q 3 :

Solution of  2x-1=|x+7| is

  • - 2

     

  • 8

     

  • - 2, 8

     

  • None of these

     

(2)

2x-1=|x+7|={x+7,if x-7-(x+7)if x<-7

  If x-7,  2x-1=x+7x=8

        If x<-7,  2x-1=-(x+7)3x=-6

 x=-2,  Not possible.



Q 4 :

Solution of  0<|3x+1|<13 is

  • (-49,-29)

     

  • [-49,-29]

     

  • (-49,-29)-{-13}

     

  • [-49,-29]-{-13}

     

(3)

Let us first solve |3x+1|<13

-13<3x+1<13-43<3x<-23

-49<x<-29

Also, 0<|3x+1| is satisfied by each x except when

3x+1=0, i.e., x=-13

  Solution is (-49,-29)-{-13}



Q 5 :

The set of real values of x satisfying the inequality 

|x2+x-6|>6, is

|x-2|+|x+2|<4 is

  • (-4,3)

     

  • (-3,2)

     

  • (-4,-3)(2,3)

     

  • (-4,-1)(0,3)

     

(4)

We have,  |x2+x-6|<6

 -6<x2+x-6<6

 -6<x2+x-6  and  x2+x-6<6

 x2+x>0  and  x2+x-12<0

 x(x+1)>0  and  (x+4)(x-3)<0

 x(-,-1)(0,)  and  -4<x<3

 x(-4,-1)(0,3)



Q 6 :

For |x-1|x+2<1x lies in the interval

  • (-,-2)(-12,)

     

  • (-,1)[2,3]

     

  • (-,-4)

     

  • [-12,1]

     

(1)

Case I:  |x-1|=x-1,  x1

  |x-1|x+2<1x-1x+2<1x-1x+2-1<0-3x+2<0

 3x+2>0  which is possible when x>-2

But it is true for x1, so common solution is x1 or x[1,)           ...(i)

Case II:  |x-1|=-x+1, x<1

  |x-1|x+2<1-x+1x+2<1x-1x+2+1>02x+1x+2>0

 x<-2  or  x>-12

But x<1, so x(-,-2)(-12,1)                  ...(ii)

  From (i) and (ii), x lies in the interval

(-,-2)(-12,1)[1,)    or    x(-,-2)(-12,)



Q 7 :

The set of all real x satisfying the inequality  3-|x|4-|x|0 is

  • [-3,3](-,-4)(4,)

     

  • (-,-4)(4,)

     

  • (-,-3)(4,)

     

  • (-,-3)(3,)

     

(1)

Case I: When x0

  |x|=x

 3-|x|4-|x|=3-x4-x0(3-x)(4-x)(4-x)20

 (x-3)(x-4)0 and x4x3 or x>4

But x0, so x[0,3](4,)                                    ...(i)

Case II: When x<0

  |x|=-x

 3-|x|4-|x|=3+x4+x0(x+3)(x+4)(x+4)20

 (x+3)(x+4)0 and x-4

 x<-4 or x-3

But x<0, so x(-,-4)[-3,0)                         ...(ii)

From (i) and (ii), x lies in the interval

(-,-4)[-3,3](4,)



Q 8 :

Solution of |x-1||x-3| is

  • x2

     

  • x2

     

  • [1, 3]

     

  • None of these

     

(2)

We have,  |x-1|-|x-3|0

Also, |x-1|-|x-3|={-2,if x<12x-4,if 1x32,if x>3

If x<1-20, not possible

If 1x3

2x-40x2x[2,)x[2,3]

If x>3

20x(3,)

Combining above, we get  x[2,)



Q 9 :

If |2x-3|<|x+5|, then x lies in the interval

  • (-3, 5)

     

  • (5, 9)

     

  • (-23,8)

     

  • (-8,23)

     

(3)

We have,  |2x-3|<|x+5|                  ...(i)

Let x32, then 2x-30 and x+50

Thus, 2x-3<x+5x<8

Thus x[32,8) satisfies the above inequality for x32

Now, let -5x<32

Then, 2x-3<0 and x+50

So, 3-2x<x+53x>-2x>-23

But, -5x<32

Thus, x(-23,32) satisfies the given inequality (i).

Also, let x<-5. Then, 2x-3<0 and x+5<0

3-2x<-5-xx>8                           ...(ii)

However, x<-5

  The above inequality (ii) does not hold.

We have checked all the required intervals.

  x[32,8)(-23,32)x(-23,8)



Q 10 :

The solution of 6x4x-1<12 is

  • x<-18

     

  • -18<x<14

     

  • x<-18 and x>14

     

  • x>18

     

(2)

Given inequality is, 6x4x-1<1212x4x-1<1

12x4x-1-1<08x+14x-1<0                 (i)

For above inequality (i), we have two cases either

(I)  8x+1>0, 4x-1<0  or  (II)  8x+1<0, 4x-1>0

From (I), we get  x>-18, x<14

   x(-18,14)                                 (ii)

From (II), x<-18, x>14, both of which can not be true

    (ii) represents the solution set of given inequality.



Q 11 :

If  |x-1|+|x-3|8, then the values of x lie in the interval

  • (-,-2]

     

  • [-2, 6]

     

  • (-3, 7)

     

  • (-2,)

     

(2)

Here two cases arises,

Case 1: When -<x1

Then, (x-1)0, x-3<0

 |x-1|=-(x-1)  and  |x-3|=-(x-3)

Now,  |x-1|+|x-3|8  -(x-1)-(x-3)8

 -2x+48x-2           (i)

Case 2: When 3x<

  |x-1|=(x-1)  and  |x-3|=(x-3)

Now, |x-1|+|x-3|8

 x-1+x-382x-48x6          (ii)

From (i) and (ii), we get x[-2, 6]



Q 12 :

If  |x-2|1, then

  • x(1, 3)

     

  • x(-1, 3)

     

  • x[1, 3]

     

  • x[-1, 3)

     

(3)

Here, |x-2|1

 -1x-211x3x[1, 3]



Q 13 :

If  |x-3|x-3>0, then

  • x(-3,)

     

  • x(3,)

     

  • x(2,)

     

  • x(1,)

     

(2)

Given, |x-3|x-3>0

 |x-3|>0x-3>0x>3

  x(3,)



Q 14 :

If  |x+5|10, then

  • x(-15, 5]

     

  • x(-5, 5]

     

  • x(-,-15][5,)

     

  • x[-,-15][5,)

     

(3)

We know that |x-a|r

 xa-r or xa+r

  |x+5|10x-5-10, or x-5+10

 x-15 or x5x(-,-15] or x[5,)

 x(-,-15][5,)



Q 15 :

The solution set of the rational inequality x+9x-60 is

  • (-,9)(6,)

     

  • (-,9](6,)

     

  • (-,9][6,)

     

  • [-9, 6)

     

(4)

We have, x+9x-60

Case I: x+90 and x-6<0

 x-9 and x<6-9x<6            (i)

Case II: x+90 and x-6>0x-9 and x>6

which is not possible simultaneously.

  Required solution set is  [-9, 6).



Q 16 :

The solution set of the inequality -23x+22<7 is

  • {x:3x<4}

     

  • {x:-2x<3}

     

  • {x:-2x<4}

     

  • {x:0x<6}

     

(3)

We have, -23x+22<7

 -43x+2<14-63x<12-2x<4



Q 17 :

Which of the following is incorrect for the solution set of the inequation ||x|-1|<|1-x|, xR, is

  • (-1, 1)

     

  • (0, )

     

  • (-1, )

     

  • (-, -1)

     

Select one or more options

(1, 2, 3)

Let us consider the following cases:

Case I: When x0

In this case, we have |x|=x

   ||x|-1|<|1-x|

 |x-1|<|x-1|, which is not true for x0

Case II: when x<0

|x|=-x

  ||x|-1|<|1-x|

        =|-x-1|<|1-x|=|x+1|<|x-1|

If x<-1, then |x+1|=-(x+1) and |x-1|=-(x-1)

  |x+1|<|x-1|=-(x+1)<-(x-1)

 -1<1, which is always true.

Thus, (-,-1) is the solution set.

If -1<x<0, then |x+1|=x+1, |x-1|=-(x-1)

  |x+1|<|x-1|=x+1<-(x-1)2x<0x<0

But, -1<x<0.

Therefore, x(-1,0).

Hence, (-,0) is the solution set.



Q 18 :

If mx2-9mx+5m+1>0 and m[p,q16), then p+q= _________ .



(4)

mx2-9mx+(5m+1)>0

 m>0 and D<0m(61m-4)<0

 m[0,461)p=0, q=4

 p+q=4



Q 19 :

If n=1983!, then the value of expression 1log2n+1log3n+1log4n++1log1983n is _________.



(1)

1log2n+1log3n+1log4n++1log1983n

=logn2+logn3++logn1983

=logn(2·3·41983)=logn1983!=lognn=1



Q 20 :

The value of (127)2-(log5162log59)=0.pq, then p+q= ________ .



(1)

2-log5162log59=2-log516log581=2-log8116

=2-log32=log39-log32=log392

(127)log392=(3-32)log392=3log3(92)-32

(92)-32=(29)32=2227=0.10=0.pq

  p+q=1+0=1



Q 21 :

If (3x)log3=(4y)log44logx=3logy then x+yx-y= __________.



(7)

Taking log on both sides, we get

log3(log3+logx)=log4(log4+logy)

logx·log4=logy·log3

  logx=-log3, logy=-log4

  x=13, y=14x+yx-y=7



Q 22 :

Number of integers in the solution set of |x-1|log2(4-x)<|x-1|log2(1+x) are ________.



(2)

4-x>0, 1+x>0x(-1,4)            (i)

Let |x-1|<1x(0,2)                         (ii)

The inequality implies log2(4-x)>log2(1+x)

  4-x>1+x

  x<32                                                (iii)

From (i), (ii) and (iii)   x(0,32)

Let |x-1|>1x(-,0)(2,)       (iv)

The inequality implies  log2(4-x)<log2(1+x)

  4-x<1+xx>32                            (v)

(i), (iv), (v) x(2,4)

Finally, we have  x(0,32)(2,4)

    Number of integers = 2



Q 23 :

A manufacturer has 800 L of a 10% solution of acid. The range of 35% acid to be added to it is (a, b) such that the acid content in the resultant mixture will be more than 15% but less than 25%, then a+b= ________.



(1400)

Let x L of 35% acid solution is added to the solution.

Total mixture=(x+800) L

According to question,

             35% of x+10% of 800>15% of (x+800)

and       35% of x+10% of 800<25% of (x+800)

  15100(800+x)<35100x+10100×800

and     25100(800+x)>35100x+10100×800

  12000+15x<35x+8000  and  20000+25x>35x+8000

  4000<20x  and  12000>10x

  200<x  and  1200>x  i.e.,  200<x<1200

Thus,  a=200,  b=1200

Hence, a+b=200+1200=1400