Aptitude - Simplification - Discussion
Discussion Forum : Simplification - General Questions (Q.No. 4)
4.
If a - b = 3 and a2 + b2 = 29, find the value of ab.
Answer: Option
Explanation:
2ab = (a2 + b2) - (a - b)2
= 29 - 9 = 20
ab = 10.
Discussion:
107 comments Page 3 of 11.
Sunil said:
5 years ago
Simply tack, a-b=3 n square on both side .
A square + b square - 2AB=3 square----------> (1).
29-2AB=9 HENCE 2AB=29-9> 2AB=20 SO AB=10.
A square + b square - 2AB=3 square----------> (1).
29-2AB=9 HENCE 2AB=29-9> 2AB=20 SO AB=10.
(1)
Gween said:
8 years ago
Please give me the answer of this? I don't get it.
What are the values of a and b in the equation 2a+3b = 5 if the sum of a and b is 4?
What are the values of a and b in the equation 2a+3b = 5 if the sum of a and b is 4?
Karthi said:
8 years ago
2ab = (a2 + b2) - (a - b)2.
=> a - b = 3
(a - b)2
(3)2 =9
=> a2 + b2 = 29
(a2 + b2)
=29.
Therefore 29-9 = 20,
2ab = 20,
ab =10.
=> a - b = 3
(a - b)2
(3)2 =9
=> a2 + b2 = 29
(a2 + b2)
=29.
Therefore 29-9 = 20,
2ab = 20,
ab =10.
Deepika said:
3 years ago
a-b = 3
a^2 + b^2 = 29.
To find ab;
Let's consider A as 5 and B as 2.
a - b = 3,
5 - 2 = 3,
a^2 = 25,
b^2 = 4.
ab = 5 * 2 = 10.
a^2 + b^2 = 29.
To find ab;
Let's consider A as 5 and B as 2.
a - b = 3,
5 - 2 = 3,
a^2 = 25,
b^2 = 4.
ab = 5 * 2 = 10.
(36)
Amit said:
9 years ago
It's so easy Easy method.
Given.
a - b = 3 and a * a - b * b = 3,
So,
a = 5 and b = 2.
Then,
ab = 5 * 2 = 10.
Given.
a - b = 3 and a * a - b * b = 3,
So,
a = 5 and b = 2.
Then,
ab = 5 * 2 = 10.
Vamshi said:
1 decade ago
A-B = 3.
A^2+B^2 = 29.
Squaring on both sides.
(A-B) ^2 = 3^2.
A^2+B^2-2AB = 9.
29-2AB =9.
20 = 2AB.
AB = 10.
A^2+B^2 = 29.
Squaring on both sides.
(A-B) ^2 = 3^2.
A^2+B^2-2AB = 9.
29-2AB =9.
20 = 2AB.
AB = 10.
Satheesh M said:
1 decade ago
a^2 + b^2 = 29
a^2 + b^2 = 5x5 + 2x2
a^2 + b^2 = 25+4
so that a = 5 and b = 2
then ab = 5x2 => 10
a^2 + b^2 = 5x5 + 2x2
a^2 + b^2 = 25+4
so that a = 5 and b = 2
then ab = 5x2 => 10
Deep goel said:
1 decade ago
a+b=3 a-b=1 then ab=?
((a+b)^2-(a-b)^2)/4=ab :^2=squaring.
(3^2-1^2)/4= ab.
(9-1)/4=ab.
8/4=2=ab.
((a+b)^2-(a-b)^2)/4=ab :^2=squaring.
(3^2-1^2)/4= ab.
(9-1)/4=ab.
8/4=2=ab.
Mohamed said:
8 years ago
Can anyone explain this to me I found it confused it.
If (a+b) / (a-b) +3/7, what is the value a/b?
If (a+b) / (a-b) +3/7, what is the value a/b?
Adwait Phadke said:
8 years ago
@Deepa.
a/b=2/3
so 3a=2b
Substituting 3a=2b in eqn
3a+5b/3a-5b
=2b+5b/2b-5b
=7b/-3b.
=-7/3.
a/b=2/3
so 3a=2b
Substituting 3a=2b in eqn
3a+5b/3a-5b
=2b+5b/2b-5b
=7b/-3b.
=-7/3.
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