Question

The least value of x, for which the expression x2+ x + 17 will not give a prime number, is

पर्याय

• 7

• 11

• 13

• 17

Answer 1

  17

Explanation:

Solving with help of option in x² + x +17

x = 7 : 49 + 7 + 17 = 73  .............(prime)
x = 11 : 121 + 11+ 17 = 149 ........(prime)
x = 13 : 169 + 13 + 17 = 199 ........(prime)
x = 17 : 289 + 17 + 17 = 323  ....(composite)
or  x² + x +17
      17² + 17 + 17
      17 (17 + 1 + 1)
     = 17 × 19 is composite