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 8 of 11.
Rowwah said:
8 years ago
(a-b)^2 = a^2 + b^2 - 2ab,
(3)^2 = 29 - 2ab,
2ab = 29 - 9 = 20
ab = 10.
(3)^2 = 29 - 2ab,
2ab = 29 - 9 = 20
ab = 10.
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?
Pramod kumar said:
8 years ago
Simple solution:
a - b = 3 ---> (1);
a^2+b^2 = 29 ---> (2);
Then we add 2ab and subtract 2ab in equation 2;
a^2+b^2 - 2ab+2ab = 29;
Then we get,
(a - b)^2+2ab = 29.
2ab = 29 - (a - b)^2.
Then we put value of a - b=3;
2ab=29 - 9;
2ab = 20;
ab = 10.
a - b = 3 ---> (1);
a^2+b^2 = 29 ---> (2);
Then we add 2ab and subtract 2ab in equation 2;
a^2+b^2 - 2ab+2ab = 29;
Then we get,
(a - b)^2+2ab = 29.
2ab = 29 - (a - b)^2.
Then we put value of a - b=3;
2ab=29 - 9;
2ab = 20;
ab = 10.
Sachin Kumar said:
8 years ago
@Gween.
a + b = 4
means a=4-b.
Put this value in the equation
5= 2(4-b)+3b,
5= 8-2b+3b,
5-8 = -2b+3b,
-3= b.
Put the value of b in the equation and u will get the value of a.
Thats it!
a + b = 4
means a=4-b.
Put this value in the equation
5= 2(4-b)+3b,
5= 8-2b+3b,
5-8 = -2b+3b,
-3= b.
Put the value of b in the equation and u will get the value of a.
Thats it!
Sachin Kumar said:
8 years ago
If a^2+b^2 = (a+b)^2.
And (a+b)^2 = a^2+b^2+2ab.
It means a^2+b^2 = a^2+b^2+2ab.
But How Could it Possible,
Please somebody tell me what actually is it?
And (a+b)^2 = a^2+b^2+2ab.
It means a^2+b^2 = a^2+b^2+2ab.
But How Could it Possible,
Please somebody tell me what actually is it?
Sourav Das said:
8 years ago
If a+b = √5 & a-b= √3 than find the value of a2 + b2.
MBA P said:
8 years ago
If a * b = 3a - 2b.
Find (4*2)*7 WHAT DOES THIS MEAN?
EXPLAIN ME PLEASE.
Find (4*2)*7 WHAT DOES THIS MEAN?
EXPLAIN ME PLEASE.
Abid said:
8 years ago
Please solve this problem.
If √a + √b- √c = 0 Then find (a+b-c)^2.
If √a + √b- √c = 0 Then find (a+b-c)^2.
Akhthar khilji said:
8 years ago
Please verify this, is it right or wrong?
My method is
As a^2+b^2=29
(a+b)(a-b)=29----> 1
Given a-b=3----> 2
Put 2 in 1
(a+b)3=29----> 3
(a+b)=29/3
(a+b)=9.6666----> 4
Putting 4 in 3
9.6666 * 3=29.
Thus it satisfies the equation,
29 = 29.
My method is
As a^2+b^2=29
(a+b)(a-b)=29----> 1
Given a-b=3----> 2
Put 2 in 1
(a+b)3=29----> 3
(a+b)=29/3
(a+b)=9.6666----> 4
Putting 4 in 3
9.6666 * 3=29.
Thus it satisfies the equation,
29 = 29.
Ashif rahim said:
8 years ago
Answer : A=5 & B=2. AB = 10.
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