Algebra

12
Question 1
If x3 + y3 = 9 and x + y = 3, then the value of x4+y4 is,
A
21
B
0
C
17
D
25
Algebra    
Discuss it


Question 1 Explanation: 
x3+y3 = (x + y) × (x2 − xy + y2)

Putting given values of x3+y3 and (x + y)
9 = 3 × ((x+y)2 − 3xy)
  = 3 × (9 − 3xy) 
  = 27 − 9xy

9xy = 18
xy = 2

x4 + y4 = (x2 + y2)2 - 2x2y2
   = (x2 + y2)2 - 2*4 
                                  [Putting value of xy]
   = ((x + y)2 - 2xy)2 - 2*4 
                            [Putting values of (x+y) and xy]
   = (9 - 4)2 - 2*4 
   = 17
Question 2
If x+1/2x = 2, find the value of 8x3+1/x3
A
40
B
20
C
28
D
35
Algebra    
Discuss it


Question 3
For any real number x the maximum value of 4−6x−x2 is at x=,
A
4
B
6
C
-3
D
3
Algebra    
Discuss it


Question 3 Explanation: 
Differentiate and equate to 0 6+2x =0 x=−3
Question 4
If 5√x +12√x =13√x then value of x is,
A
2
B
1
C
3
D
4
Algebra    
Discuss it


Question 4 Explanation: 
say x=1
17!=13

for, x=2 and 3 also not possible
x=4
52+122=132
169=169
Question 5
if x = (√2 + 1 )-1⁄5 then the value of (x5 - 1⁄x5)
A
0
B
-2
C
2
D
4
Algebra    
Discuss it


Question 5 Explanation: 
1_q_sol
Question 6
If b2 + 1⁄b2 = 1, then value of b3 + 1⁄b3 is ,
A
0
B
6
C
-4
D
4
Algebra    
Discuss it


Question 6 Explanation: 
E = (b + 1⁄b)(b2 - 1 + 1⁄b2)
Question 7
If x1/3 + y1/3 - z1/3 = 0 then value of (x + y - z)3 + 27xyz is
A
8
B
2
C
0
D
6
Algebra    
Discuss it


Question 7 Explanation: 
x1/3 + y1/3 = z1/3
Now cubing both sides we get 
x + 3x1/3y1/3(x1/3 + y1/3) + y = z
or, (x + y - z) = -3x1/3y1/3z1/3
Cubing again both sides, (x + y - z) = -27xyz.
So answer is zero
Question 8
{\mathbf{y^{y{\sqrt[]{y}}}} = {\mathbf{(y\sqrt{y})^{y}}} then y is equal to,
A
9/4
B
7/4
C
1/4
D
5/4
Algebra    
Discuss it


Question 8 Explanation: 
Now equating power on both side, y \sqrt{y} = \frac{3y}{2} or or
Question 9
If ab+bc+ac = 0, then the value of \frac{1}{a^{2}-bc} + \frac{1}{b^{2}-ac} + \frac{1}{c^{2}-ab}
A
6
B
2
C
3
D
0
Algebra    
Discuss it


Question 9 Explanation: 
Put -ac = ab + bc ; -ab = ac+ bc and -bc =ab + ac
(ab + bc + ca)/[(a+b+c)(abc)]
as, ab+bc+ca=0
= 0
Question 10
Following instructions are to be used throughout the quiz:

Each of the questions given below consists of a statement and/or a question and two statements numbered I and II given below it. You have to decide whether the data provided in the statement(s) is/are sufficient to answer the given question.
Read both the statements and Give answer
(a) if the data in Statement I alone is sufficient to answer the question, while the data in Statement II alone is not sufficient to answer the question.
(b) if the data in Statement II alone is sufficient to answer the question, while the data in Statement I alone is not sufficient to answer the question.
(c) if the data in each Statement I and Statement II alone is sufficient to answer the question.
(d) if the data even in both Statements I and II together are not sufficient to answer the question.
(e) if the data in both Statements I and II together are necessary to answer the question.

If x,y are integers, then (x2 + y2)1/2 is an integer?
I) x2 + y2 is an integer
II) x2 - 3y2 = 0
A
A
B
B
C
C
D
D
E
E
Algebra    Data Sufficiency    
Discuss it


There are 19 questions to complete.
12


My Personal Notes arrow_drop_up