Let 2 < < and = - 12 2. Then the value of ( 15 2 )( 8 + 8 ) + ( 15 2 )( 8 - 8 ) is equal to :
- 2 - 1 3
- 2 3
- 1 - 2 3
- - 2 3
Answer
(3) 1 - 2 3
Solution
Let A = 15 2, B = 8 . Expression
= ( - ) + ( + )
= (A - B) + (A - B)
= (- 2 ) + (- 2 ) = 2 - 2
4 < 2 < 2, 2 > 2 the value is negative.
= - 12 2, in the second quadrant = 2 23
( 2 - 2 )2 = 1 - = 3 - 2 23 = ( 2 - 1)23
Value = - 2 - 1 3 = 1 - 2 3
Answer: (3)