AP EAMCET2013MathematicsTrigonometric Ratios & Identities
If + =p and ^3 + ^3 =q , then p (p^2-3 ) is equal to
Options
- Aq
- B2 q
- C-q
- D-2 q
Correct answer
D. -2 q
Step-by-step solution
aligned & Given, + =p & and ^3 + ^3 =q & ( + ) & ( ^2 - + ^2 )=q aligned p(1- )=q [From Eq. (i) and ^2 + ^2 =1 ] aligned & 1- = q p & =1- q p aligned On squaring both sides of Eq. (i), we get aligned & ^2 + ^2 +2 =p^2 & 1+2 (1- q p )=p^2 [from Eq. (iii)] & p+2(p-q)=p^3 & 3 p-2 q=p^3 & p^3-3 p=-2 q & p (p^2-3 )=-2 q & aligned