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
12
15
18
Answer: Option
Explanation:

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

   = 29 - 9 = 20

   ab = 10.

Discussion:
107 comments Page 10 of 11.

Kanishka said:   8 years ago
If x+1/x=3, then find the value of x^3+1/x^3.

Arpitha sharma said:   8 years ago
Here, (2a-3b) (4a^+6ab+9b^) +27b^3.

Bubhiramsingh said:   8 years ago
If log ab=log(a+b) then proved(a+b)2-(a-b)2 = 4(a+b).

Chirag said:   8 years ago
I didn't understand. Please tell me.

Imane said:   8 years ago
What about if its: find the value of a and b and we have just a+b=2 and ab=-5?

Shanto said:   8 years ago
a/b=4a, 2b=12, than what is the value of a? or is it wrong?

Rushabh said:   8 years ago
log(a+b/2) = 1/2(loga+logb) so prove that a^2+b^2=4ab is that possible.

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.

Dharmender meena said:   8 years ago
(a-b)2=a2+b2-2ab.

9=29-2ab,
2ab=29-9,
ab=20/2,
ab=10.

Dinesh said:   8 years ago
Let us assume a=5, b=2.

a^+b^=25+4=29.

a-b =5-2=3.

So ab=5*2=10.


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