BITSAT2017MathematicsApplication of DerivativesActual
Line joining the points ( 0 , 3 ) and ( 5 , - 2 ) is a tangent to the curve y = a x 1 + x , then
Options
- Aa = 1 ± 3
- Ba ∈ ϕ
- Ca = - 1 ± 3
- Da = - 2 ± 2 3
Correct answer
B. a ∈ ϕ
Step-by-step solution
Equation of line joining the points ( 0 , 3 ) and ( 5 , - 2 ) is y = 3 - x . If this line is tangent to y = a x ( x + 1 ) , then ( 3 - x ) ( x + 1 ) = a x should have equal roots. Thus, ( a - 2 ) 2 + 12 = 0 ⇒ No value of a ⇒ a ∈ ϕ