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.
10
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15
18
Answer: Option
Explanation:

2ab = (a2 + b2) - (a - b)2

   = 29 - 9 = 20

   ab = 10.

Discussion:
107 comments Page 5 of 11.

Neeraj Kashyap said:   9 years ago
Please solve the following with explanation:

1. (a + b) (a - b) + (2a + b) (2a - 3b).
2. (x - y)(2x + y) - (x + y)(2x - y).
3. (x + 6){5x - 3(x - 2)}
4. 7x - 3{x - 2x(x - 4)}

Anil malav said:   9 years ago
(a^2 + b^2)^1/2 = 613 then find the value of a+b.

Solve and find the answer.

Rah1 said:   9 years ago
Awesome answer @Ram.

Francium said:   9 years ago
Guys, please solve this for me a2 + b2 = 36 and an=7 find the value of (a+b)2.

Gyanika said:   9 years ago
Can somebody please solve this question.

a - b = 1, 2a + 20 = b. Then a, b is?

Sonali said:   9 years ago
a-b = 3, a2+b2=29, ab =?
(a-b)2 = a2+b2-2ab
2ab = (a2+b2)-(a-b)2
ab = 29-9/2
= 20/2 = 10 Ans.

Tanim Ehsan said:   9 years ago
If a + b = 13 and ab = 3 then (a+2b)^2-5b^2 = ?

Simplify the solution.

Bonjor said:   9 years ago
I would be grateful if anyone answers this question.

If a-b=4 and ab=60 then find the value of a+b.

I found that the answer is + or - 16 what is + or -? Please tell me.

Harsh singh said:   9 years ago
Yes @Bonjor.

(a+b)2 = (a-b)2+4ab,
(a+b)2 = 256,
a+b = +-16.
+-16 is the answer.

Venkat@rockzzzz said:   9 years ago
(a-b)^2 = a^2+b^2-2ab.
2ab = a^2+b^2-(a-b)^2,
= 29-3^2,
= 29-9,
2ab = 20.
ab =10.


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