The product of all the rational roots of the equation (x2-9x+11)2-(x-4)(x-5)=3, is equal to
- 7
- 21
- 28
- 14
Answer
(4) 14
Solution
Put t=x2-9x: (t+11)2-(t+20)=3 t2+21t+98=0
t=-7 or -14
t=-7: x2-9x+7=0, D=53 not a perfect square irrational
t=-14: x2-9x+14=0 x=2, 7
Product of rational roots =2 7=14
Answer: (4)