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algebra - 05
01.
The simplified value of following is:
(
3
15
a
5
b
6
c
3
×
5
9
a
b
5
c
4
)
(
3
15
a
5
b
6
c
3
×
5
9
a
b
5
c
4
)
÷
10
17
a
2
b
c
3
10
17
a
2
b
c
3
1
3
10
a
b
4
c
3
3
10
a
b
4
c
3
2
9
10
a
2
b
c
4
9
10
a
2
b
c
4
3
9
10
a
2
b
c
4
9
10
a
2
b
c
4
4
1
10
a
4
b
4
c
10
1
10
a
4
b
4
c
10
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Report
Answer:-
1
Explanation:-
Solution:
(
3
15
a
5
b
6
c
3
×
5
9
a
b
5
c
4
)
÷
10
27
a
2
b
c
3
⇒
1
9
a
6
b
11
c
7
÷
10
27
a
2
b
c
3
⇒
1
9
a
6
b
11
c
7
10
27
a
2
b
c
3
⇒
3
10
a
4
b
10
c
4
(
3
15
a
5
b
6
c
3
×
5
9
a
b
5
c
4
)
÷
10
27
a
2
b
c
3
⇒
1
9
a
6
b
11
c
7
÷
10
27
a
2
b
c
3
⇒
1
9
a
6
b
11
c
7
10
27
a
2
b
c
3
⇒
3
10
a
4
b
10
c
4
02.
If a
2
+ b
2
+ c
2
= 2(a - b - c) -3, then the value of a + b + c is?
1
-2
2
1
3
2
4
-1
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Answer:-
1
Explanation:-
Solution:
a
2
+
b
2
+
c
2
=
2
(
a
−
b
−
c
)
−
3
⇒
a
2
+
b
2
+
c
2
=
2
a
−
2
b
−
2
c
−
3
⇒
a
2
+
b
2
+
c
2
−
2
a
+
2
b
+
2
c
+
3
=
0
⇒
a
2
−
2
a
+
1
+
b
2
+
2
b
+
1
+
c
2
+
2
c
+
1
=
0
⇒
(
a
−
1
)
2
+
(
b
+
1
)
2
+
(
c
+
1
)
2
=
0
(
a
−
1
)
2
=
0
(
b
+
1
)
2
=
0
(
c
+
1
)
2
=
0
⇒
a
−
1
=
0
⇒
b
+
1
=
0
⇒
c
+
1
=
0
⇒
a
=
1
⇒
b
=
−
1
⇒
c
=
−
1
∴
a
+
b
+
c
=
1
−
1
−
1
=
−
1
a
2
+
b
2
+
c
2
=
2
(
a
−
b
−
c
)
−
3
⇒
a
2
+
b
2
+
c
2
=
2
a
−
2
b
−
2
c
−
3
⇒
a
2
+
b
2
+
c
2
−
2
a
+
2
b
+
2
c
+
3
=
0
⇒
a
2
−
2
a
+
1
+
b
2
+
2
b
+
1
+
c
2
+
2
c
+
1
=
0
⇒
(
a
−
1
)
2
+
(
b
+
1
)
2
+
(
c
+
1
)
2
=
0
(
a
−
1
)
2
=
0
(
b
+
1
)
2
=
0
(
c
+
1
)
2
=
0
⇒
a
−
1
=
0
⇒
b
+
1
=
0
⇒
c
+
1
=
0
⇒
a
=
1
⇒
b
=
−
1
⇒
c
=
−
1
∴
a
+
b
+
c
=
1
−
1
−
1
=
−
1
03.
If x(x + y + z) = 20, y = (x + y + z) = 30 & z(x + y + z) = 50, then the value of 2(x + y + z) is?
1
20
2
10
3
15
4
18
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Answer:-
1
Explanation:-
Solution:
Put
(
x
+
y
+
z
)
=
10
x
=
2
y
=
3
z
=
5
x
(
x
+
y
+
z
)
=
20
⇔
2
(
10
)
=
20
⇔
20
=
20
Similarly other will satisfied,
So, value of 2
(
x
+
y
+
z
)
=
2
(
10
)
=
20
Put
(
x
+
y
+
z
)
=
10
x
=
2
y
=
3
z
=
5
x
(
x
+
y
+
z
)
=
20
⇔
2
(
10
)
=
20
⇔
20
=
20
Similarly other will satisfied,
So, value of 2
(
x
+
y
+
z
)
=
2
(
10
)
=
20
04.
If x = y = z, then
(
x
+
y
+
z
)
2
x
2
+
y
2
+
z
2
(
x
+
y
+
z
)
2
x
2
+
y
2
+
z
2
is?
1
2
2
3
3
1
4
4
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Answer:-
1
Explanation:-
Solution:
(
x
+
y
+
z
)
2
x
2
+
y
2
+
z
2
Assume
x
=
y
=
z
=
1
⇔
(
1
+
1
+
1
)
2
1
+
1
+
1
⇔
9
3
⇔
3
(
x
+
y
+
z
)
2
x
2
+
y
2
+
z
2
Assume
x
=
y
=
z
=
1
⇔
(
1
+
1
+
1
)
2
1
+
1
+
1
⇔
9
3
⇔
3
05.
If
x
y
=
a
+
2
a
−
2
,
x
y
=
a
+
2
a
−
2
,
then the value of
x
2
−
y
2
x
2
+
y
2
x
2
−
y
2
x
2
+
y
2
= ?
1
2
a
a
2
+
2
2
a
a
2
+
2
2
4
a
a
2
+
4
4
a
a
2
+
4
3
2
a
a
2
+
4
2
a
a
2
+
4
4
4
a
a
2
+
2
4
a
a
2
+
2
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Workspace
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Answer:-
1
Explanation:-
Solution:
x
y
=
a
+
2
a
−
2
x
2
y
2
=
(
a
+
2
)
2
(
a
−
2
)
2
x
y
=
a
+
2
a
−
2
x
2
y
2
=
(
a
+
2
)
2
(
a
−
2
)
2
Applying componendo and dividendo
∴
x
2
−
y
2
x
2
+
y
2
=
(
a
+
2
)
2
−
(
a
−
2
)
2
(
a
+
2
)
2
+
(
a
−
2
)
2
=
8
a
2
a
2
+
8
=
4
a
a
2
+
4
∴
x
2
−
y
2
x
2
+
y
2
=
(
a
+
2
)
2
−
(
a
−
2
)
2
(
a
+
2
)
2
+
(
a
−
2
)
2
=
8
a
2
a
2
+
8
=
4
a
a
2
+
4
06.
If
x
−
1
x
=
2
,
x
−
1
x
=
2
,
then the value of the following is
x
3
−
1
x
3
x
3
−
1
x
3
= ?
1
2
2
11
3
15
4
14
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Answer:-
1
Explanation:-
Solution:
x
−
1
x
=
2
to find
x
3
−
1
x
3
⇒
x
−
1
x
=
2
[
Cubing both sides
]
⇒
(
x
−
1
x
)
3
=
(
2
)
3
⇒
x
3
−
1
x
3
−
3
×
x
×
1
x
(
x
−
1
x
)
=
8
⇒
x
3
−
1
x
3
−
3
×
(
2
)
=
8
⇒
x
3
−
1
x
3
=
14
x
−
1
x
=
2
to find
x
3
−
1
x
3
⇒
x
−
1
x
=
2
[
Cubing both sides
]
⇒
(
x
−
1
x
)
3
=
(
2
)
3
⇒
x
3
−
1
x
3
−
3
×
x
×
1
x
(
x
−
1
x
)
=
8
⇒
x
3
−
1
x
3
−
3
×
(
2
)
=
8
⇒
x
3
−
1
x
3
=
14
07.
If a
2
+ b
2
+ c
2
- ab - bc - ca = 0 then a : b : c is?
1
1 : 2 : 1
2
2 : 1 : 1
3
1 : 1 : 2
4
1 : 1 : 1
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Answer:-
1
Explanation:-
Solution:
Given,
a
2
+
b
2
+
c
2
−
a
b
−
b
c
−
c
a
=
0
Find,
a
:
b
:
c
=
?
According to the question,
a
2
+
b
2
+
c
2
−
a
b
−
b
c
−
c
a
=
0
⇒
a
2
+
b
2
+
c
2
=
a
b
+
b
c
+
c
a
Let
a
=
b
=
c
=
1
⇒
1
2
+
1
2
+
1
2
=
1
×
1
+
(
1
×
1
)
+
(
1
×
1
)
⇒
3
=
3
⇒
So, ratio of
a
:
b
:
c
=
1
:
1
:
1
Given,
a
2
+
b
2
+
c
2
−
a
b
−
b
c
−
c
a
=
0
Find,
a
:
b
:
c
=
?
According to the question,
a
2
+
b
2
+
c
2
−
a
b
−
b
c
−
c
a
=
0
⇒
a
2
+
b
2
+
c
2
=
a
b
+
b
c
+
c
a
Let
a
=
b
=
c
=
1
⇒
1
2
+
1
2
+
1
2
=
1
×
1
+
(
1
×
1
)
+
(
1
×
1
)
⇒
3
=
3
⇒
So, ratio of
a
:
b
:
c
=
1
:
1
:
1
08.
If
x
+
1
x
−
1
=
a
b
x
+
1
x
−
1
=
a
b
and
1
−
y
1
+
y
=
b
a
,
1
−
y
1
+
y
=
b
a
,
then the value of
x
−
y
1
+
x
y
x
−
y
1
+
x
y
is?
1
a
2
−
b
2
a
b
a
2
−
b
2
a
b
2
a
2
+
b
2
2
a
b
a
2
+
b
2
2
a
b
3
a
2
−
b
2
2
a
b
a
2
−
b
2
2
a
b
4
2
a
b
a
2
−
b
2
2
a
b
a
2
−
b
2
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Answer:-
1
Explanation:-
Solution:
Given ,
x
+
1
x
−
1
=
a
b
(
Using componendo & dividendo
)
⇔
x
1
=
a
+
b
a
−
b
⇔
x
=
a
+
b
a
−
b
.
.
.
.
.
(
i
)
Again,
1
−
y
1
+
y
=
b
a
⇔
1
+
y
1
−
y
=
a
b
⇔
1
y
=
a
+
b
a
−
b
⇔
y
=
a
−
b
a
+
b
.
.
.
.
.
(
i
i
)
From question,
x
−
y
1
+
x
y
⇒
a
+
b
a
−
b
−
a
−
b
a
+
b
1
+
(
a
+
b
a
−
b
)
(
a
−
b
a
+
b
)
⇒
(
a
+
b
)
2
−
(
a
−
b
)
2
(
a
2
−
b
2
)
(
1
+
1
)
⇒
4
a
b
2
(
a
2
−
b
2
)
⇒
2
b
a
2
−
b
2
Given ,
x
+
1
x
−
1
=
a
b
(
Using componendo & dividendo
)
⇔
x
1
=
a
+
b
a
−
b
⇔
x
=
a
+
b
a
−
b
.
.
.
.
.
(
i
)
Again,
1
−
y
1
+
y
=
b
a
⇔
1
+
y
1
−
y
=
a
b
⇔
1
y
=
a
+
b
a
−
b
⇔
y
=
a
−
b
a
+
b
.
.
.
.
.
(
i
i
)
From question,
x
−
y
1
+
x
y
⇒
a
+
b
a
−
b
−
a
−
b
a
+
b
1
+
(
a
+
b
a
−
b
)
(
a
−
b
a
+
b
)
⇒
(
a
+
b
)
2
−
(
a
−
b
)
2
(
a
2
−
b
2
)
(
1
+
1
)
⇒
4
a
b
2
(
a
2
−
b
2
)
⇒
2
b
a
2
−
b
2
09.
If x + y + z = 6 and xy + yz + zx = 10, then the value of x
3
+ y
3
+ z
3
- 3xyz is?
1
36
2
40
3
42
4
48
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Answer:-
1
Explanation:-
Solution:
Given
x
+
y
+
z
=
6
x
y
+
y
z
+
z
x
=
10
To find
x
3
+
y
3
+
z
3
−
3
x
y
z
= ?
⇒
Using formula,
⇒
(
x
+
y
+
z
)
2
=
x
2
+
y
2
+
z
2
+
2
(
x
y
+
y
z
+
z
x
)
⇒
6
2
=
x
2
+
y
2
+
z
2
+
2
×
10
⇒
36
=
x
2
+
y
2
+
z
2
+
20
⇒
x
2
+
y
2
+
z
2
=
16
⇒
x
2
+
y
2
+
z
2
−
3
x
y
z
=
(
x
+
y
+
z
)
(
x
2
+
y
2
+
z
2
−
x
y
−
y
z
−
z
x
)
⇒
x
2
+
y
2
+
z
2
−
3
x
y
z
=
6
[
16
−
10
]
⇒
x
2
+
y
2
+
z
2
−
3
x
y
z
=
6
×
6
⇒
x
2
+
y
2
+
z
2
−
3
x
y
z
=
36
Given
x
+
y
+
z
=
6
x
y
+
y
z
+
z
x
=
10
To find
x
3
+
y
3
+
z
3
−
3
x
y
z
= ?
⇒
Using formula,
⇒
(
x
+
y
+
z
)
2
=
x
2
+
y
2
+
z
2
+
2
(
x
y
+
y
z
+
z
x
)
⇒
6
2
=
x
2
+
y
2
+
z
2
+
2
×
10
⇒
36
=
x
2
+
y
2
+
z
2
+
20
⇒
x
2
+
y
2
+
z
2
=
16
⇒
x
2
+
y
2
+
z
2
−
3
x
y
z
=
(
x
+
y
+
z
)
(
x
2
+
y
2
+
z
2
−
x
y
−
y
z
−
z
x
)
⇒
x
2
+
y
2
+
z
2
−
3
x
y
z
=
6
[
16
−
10
]
⇒
x
2
+
y
2
+
z
2
−
3
x
y
z
=
6
×
6
⇒
x
2
+
y
2
+
z
2
−
3
x
y
z
=
36
10.
The sum of
1
x
+
y
1
x
+
y
and
1
x
−
y
1
x
−
y
is?
1
2
y
x
2
−
y
2
2
y
x
2
−
y
2
2
2
x
x
2
−
y
2
2
x
x
2
−
y
2
3
−
2
y
x
2
−
y
2
−
2
y
x
2
−
y
2
4
2
x
y
2
−
x
2
2
x
y
2
−
x
2
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Answer:-
1
Explanation:-
Solution:
According to the question,
1
x
+
y
+
1
x
−
y
=
x
−
y
+
x
+
y
x
2
−
y
2
=
2
x
x
2
−
y
2
According to the question,
1
x
+
y
+
1
x
−
y
=
x
−
y
+
x
+
y
x
2
−
y
2
=
2
x
x
2
−
y
2
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