Q41 / 90 · JEE Main 2021 (17 Mar Shift 2) · Mathematics

If x, y, z are in arithmetic progression with common difference d, x≠3d, and the determinant of the matrix 342x452y5kz is zero, then the value of k2 is

  • Correct answer
    A
    72
  • B
    12
  • C
    36
  • D
    6

Solution

Given x, y, z are in arithmetic progression, hence 2y=x+z, also 342x452y5kz=0

Applying R2→R1+R3-2R2

⇒342x0k-6205kz=0

⇒(k-62)(3z-5x)=0

⇒(k-62)=0 or (3z-5x)=0

If 3z-5x=0

⇒3(x+2d)-5x=0

⇒x=3d (Not possible)

⇒k=62

⇒k2=72.

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

Relevant Questions