What is the remainder of 67^24-54^24 when divided by 11
Answers
( 67 )²⁴ - ( 54 ) ²⁴
=( 67 ¹²)² - ( 54 ¹²)²
following the formula:- ( a²- b²) = ( a+ b ) ( a - b)
=( 67 ¹² + 54 ¹²) ( 67¹² -54¹² )
=( 67 ¹²+ 54¹² ) { ( 67⁶)² - ( 54⁶ ) ²}
=( 67 ¹²+ 54¹² )( 67⁶ +54⁶ ) ( 67⁶ - 54⁶)
=( 67 ¹²+ 54¹² )( 67⁶ +54⁶ ) { ( 67² )³ - (54 ²) ³}
let's consider ( 67² )³ = a³ and (54 ²) ³= b ³
now following this formula:- ( a³ - b³ ) = ( a - b ) ( a² + ab + b² )
=( 67 ¹²+ 54¹² )( 67⁶ +54⁶ ) (67² - 54² ) {( 67²)²+ 67² ₓ 54² + ( 54² ) ²}
=( 67 ¹²+ 54¹² )( 67⁶ +54⁶ ) ( 67 + 54 ) ( 67 - 54 ) ( 67⁴ +67² ₓ 54²+ 54⁴ )
=( 67 ¹²+ 54¹² )( 67⁶ +54⁶ ) ( 67⁴ +67² ₓ 54²+ 54⁴ ) (121 ) (13 )
=( 67 ¹²+ 54¹² )( 67⁶ +54⁶ ) ( 67⁴ +67² ₓ 54²+ 54⁴ ) ( 121 ₓ 13 )
Ans :- Remainder will be 0
121 will be divisible by 11
Remainder of 67²⁴ - 54²⁴ when divided by 11 is Zero (0).
Step 1:
Use law of indices xᵃᵇ = (xᵃ)ᵇ and write 24 as 12 x 2
67²⁴ - 54²⁴
= 67¹²ˣ² - 54¹²ˣ²
= (67¹²)² - (54¹²)²
Step 2:
Use a² - b² = (a + b)(a - b)
a = 67¹²
b = 54¹²
= (67¹² + 54¹²)(67¹² - 54¹²)
Step 3:
Writing 12 as 6 x 2 and using again a² - b² = (a + b)(a - b)
= (67¹² + 54¹²)(67⁶ + 54⁶)(67⁶ - 54⁶)
Step 4:
Writing 6 as 2 x 3 and using a³ - b³ = (a - b)(a² + b² + ab)
a = 67² , b = 54²
= (67¹² + 54¹²)(67⁶ + 54⁶) (67²- 54²)(67⁴ + 54⁴ + 67²*54²)
Step 5:
Using again a² - b² = (a -+ b)(a - b) for (67²- 54²)
= (67¹² + 54¹²)(67⁶ + 54⁶) (67 + 54)(67 - 54)(67⁴ + 54⁴ + 67²*54²)
= (67¹² + 54¹²)(67⁶ + 54⁶) (121)(13)(67⁴ + 54⁴ + 67²*54²)
Step 6:
121 is 11 x 11 hence divisible by 11 so remainder will be zero
= 11 (67¹² + 54¹²)(67⁶ + 54⁶) (11)(13)(67⁴ + 54⁴ + 67²*54²)
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