Q37 / 90 · JEE Main 2023 (12 Apr Shift 1) · Mathematics

If the total maximum value of the function fx=3e2sinxsin2x, x∈0, π2, is ke, then ke8+k8e5+k8 is equal to

  • Correct answer
    A
    e3+e6+e11
  • B
    e5+e6+e11
  • C
    e3+e6+e10
  • D
    e3+e5+e11

Solution

Given function is fx=3e2sinxsin2x

For maxima or minima f'(x)=0

f'x=fx2sinxcosx×ln3e2sinx+sin2x1×2sinx3e×3e2-1sin2x×cosx

⇒fxsin2xln3e2sinx-sinxcosx=0

Now on equation we get, sin2x=0 (not possible)

So, ln3e2sinx=+12

⇒3×e2sinx=e12

⇒sinx=32

⇒fmax=e38=e118e⇒k=e118

⇒ke8+k8e5+k8=e3+e6+e11

Hence, the correct answer is option: 'A'.

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