MHT CET202526 Apr 2025Evening ShiftMathematicsApplication of DerivativesActual
The equation of the tangent to the curve y=b e^ -x / a at the point where it crosses the Y axis is
Options
- Ax+ y = ab
- Bx a + y ~b =1
- Ca x+b y=1
- Dx+y=a+b
Correct answer
B. x a + y ~b =1
Step-by-step solution
The curve y = b e^ -x/a crosses the Y-axis at x=0 , giving the point of tangency (0, b) . The derivative is computed as dy dx = - b a e^ -x/a . At x=0 , the slope of the tangent is ( dy dx )_ x=0 = - b a . Using point-slope form with point (0, b) yields y - b = - b a x . Multiplying through by a gives a(y - b) = -b x , rearranged to b x + a y = a b . Dividing both sides by a b results in x a + y b = 1 , which corresponds to option B . The final answer is B .