Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
KVPY2016MathematicsBasics of Mathematics

Consider a cuboid all of whose edges are integers and whose base is square. Suppose the sum of all its edges is numerically equal to the sum of the areas of all its six faces. Then the sum of all its edges is.

Options

  1. A12
  2. B18
  3. C24
  4. D36

Correct answer

C. 24

Step-by-step solution

Let sides are a , a , h array l So, 4 a+4 h+4 a=2 (a²+a h+a h ) 2 a+2 h+2 a=a²+2 a h a²-4 a=2 h(1-a) (a²-1 )+1-4(a-1)-4=2 h(1-a) (a-1)(a+1)-4(a-1)-3=2 h(1-a) 2 h= 3 a-1 +4-(a+1) array So a=2 & h=2 are the only integral solution (a & h are positive integers)

Practice Basics of Mathematics on Quantrex Academy →

More from Basics of Mathematics

All Basics of Mathematics questions Full Basics of Mathematics list All KVPY PYQs