Aptitude - Numbers - Discussion
Discussion Forum : Numbers - General Questions (Q.No. 29)
29.
107 x 107 + 93 x 93 = ?
Answer: Option
Explanation:
| 107 x 107 + 93 x 93 | = (107)2 + (93)2 |
| = (100 + 7)2 + (100 - 7)2 | |
| = 2 x [(100)2 + 72] [Ref: (a + b)2 + (a - b)2 = 2(a2 + b2)] | |
| = 20098 |
Discussion:
20 comments Page 2 of 2.
Anjali said:
7 years ago
(100+7)(100+7)+(100-7)(100-7).
= 10000+700+700 + 49 + 10000-700-700 + 49.
= 20000+98 = 20098.
= 10000+700+700 + 49 + 10000-700-700 + 49.
= 20000+98 = 20098.
(5)
Hari said:
9 years ago
why can't we take it as (a + b) (a - b) = a^2 + b^2.
(107 + 93) (107 - 93).
Please explain.
(107 + 93) (107 - 93).
Please explain.
Sia said:
7 years ago
@Jonavin, @Hari.
We can't use (a+b) (a-b) because there is (a^2+b^2).
Instead of (a^2-b^2).
We can't use (a+b) (a-b) because there is (a^2+b^2).
Instead of (a^2-b^2).
Sagar HR said:
7 years ago
Or we can solve using the formula a^2+b^2=[a+b]^2- 2ab.
(107+93)^2 - 2(107*93) = 20098.
(107+93)^2 - 2(107*93) = 20098.
(2)
Ajax said:
1 decade ago
@ Mr. Milind.
Your first method is not working on 110 - 125. Please give us another method.
Your first method is not working on 110 - 125. Please give us another method.
Rakshana said:
9 years ago
@Manoj.
Is this applicable for the method of addition and multiplication?
Is this applicable for the method of addition and multiplication?
Gayu said:
1 decade ago
107*100+107*7 = 11449.
93*90+93*3 = 8649.
11449+8649 = 20098.
93*90+93*3 = 8649.
11449+8649 = 20098.
Sgyanaranjan said:
7 years ago
100+100=200.
7.7+7.7=98,
So the answer is 20098.
7.7+7.7=98,
So the answer is 20098.
(2)
Jonavin said:
8 years ago
Why we can't take a+b a-b ?
GYANARANJAN SAHOO said:
7 years ago
Thanks @Anjali.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers