AP EAMCET2004MathematicsTrigonometric Equations
The value of the series 12^ + 84^ + 132^ + 156^ is
Options
- A1 2
- B1 4
- C-1 4
- D-1 2
Correct answer
D. -1 2
Step-by-step solution
We have, aligned & 12^ + 84^ + 132^ + 156^ = & 132^ + 12^ + 156^ + 84^ = & 2 72^ 60^ +2 120^ 36^ = & 2 ( 5 -1 4 ) 1 2 +2 ( -1 2 ) ( 5 +1 4 ) = & 5 -1 4 - 5 +1 4 =- 2 4 = & - 1 2 aligned