Q41 / 90 · JEE Main 2023 (01 Feb Shift 2) · Mathematics

The number of integral values of k, for which one root of the equation 2x2-8x+k=0 lies in the interval 1,2 and its other root lies in the interval 2,3, is : 

  • A
    2
  • B
    0
  • Correct answer
    C
    1
  • D
    3

Solution

Let f(x)=2x2-8x+k=0

Figure

 

f(1)>0

f(2)<0

f(3)>0

Now, f(1)>0⇒2-8+k>0⇒k>6 ......(1)

f(2)<0⇒8-16+k<0⇒k<8 ......(2)

f(3)>0⇒18-24+k>0⇒k>6 ......(3)

From equations 1, 2 & 3,

k∈(6,8)

∴ Integral value of k=7

Therefore number of integral value of k is one

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

Relevant Questions