(2^2+4^2+6^2+.....+14^2)=?
Choose the correct option:
A) 88 B) 560 C) 99 D) 550 E) 540

Rationale: = ( 1 x 2 ) ^ 2 + ( 2 x 2 ) ^ 2 , + ( 2 x 3 ) ^ 3 + . . . . . . ( 2 x 7 ) ^ 2 = 2 ^ 2 x ( 1 ^ 2 + 2 ^ 2 + 3 ^ 2 + . . . . . . . + 7 ^ 2 ) formula is = 1 / 6 n ( n + 1 ) ( 2 n + 1 ) = ( 4 x 1 / 6 x 7 x 8 x 15 ) = ( 4 x 140 ) = 560 answer is b
Answer: B