KVPY2011MathematicsQuadratic Equation
Let a, b, x, y be real numbers such that a²+b²=81, x²+y²=121 and a x+b y=99 . Then the set of all possible values of ay - bx is -
Options
- A(0, 9 11 ]
- B(0, 9 11 )
- C0
- D[ 9 11 , )
Correct answer
C. 0
Step-by-step solution
a²+b²=81x²+y²=121a x+b y=99 (a²+b² ) (x²+y² )=(81)(121) ...(1) and (a x+b y)²=(99)² ...(2) (1)-(2) (ay -b x)²=0 ay -b x=0