without actually squaring, find the value of the following: 21²-20²
Answers
Answered by
5
To Find :
The value of 21²-20²
Solution :
We will use the identity:
(a+b)(a-b) = a²-b²
Hence,
21²-20²
= (21-20)(21+20)
= 1(41)
= 41
Hence, 21²-20² = 41
More Identities to Know :
- (a+b)² = a²+b²+2ab
- (a-b)² = a²+b²-2ab
- (x+a)(x+b) = x²+(a+b)x+ab
- (a+b+c)² = a²+b²+c²+2ab+2ac+2bc
- (a+b)³ = a³+b³+3a²b+3ab²
- (a-b)³ = a³-b³-3a²b+3ab²
Answered by
0
Answer:
21^2=21x21=441
20^2=20x20=400
Step-by-step explanation:
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