Skip to content

CA Foundation · Quantitative Aptitude · Sets, Relations and Functions, Limits and Continuity

The set B = {x : x is a natural number and x² − 7x + 12 = 0} in roster form is:

Factorising x² − 7x + 12 gives (x−3)(x−4)=0, so the roots are 3 and 4. Both are natural numbers, so the roster form is {3, 4}.

  1. A{3, 4}Correct
  2. B{-3, -4}
  3. C{3}
  4. D{2, 6}

Explanation

x² − 7x + 12 = (x−3)(x−4) = 0, so x = 3 or 4. Both are natural numbers. Check: 9−21+12=0 and 16−28+12=0. The negative pair gives wrong signs and is not natural.

Did you get it right without looking?

One question tells you little. A timed set on Sets, Relations and Functions, Limits and Continuity shows your real accuracy, how long you take and where you lose marks.

Practise Sets, Relations and Functions, Limits and ContinuityFree diagnostic mock

More Sets, Relations and Functions, Limits and Continuity questions