Question

three numbers are in ratio 2:4:5 if the sum of their cubes is 5319 find the numbers

Answer 1

let the no be 2x, 4x, 5x
According to the sum:
(2x) ^3+(4x) ^3+(5x) ^3=5319
8x^3+64x^3+125x^3=5319
197x^3=5319
x^3=27
x=3
The no are:
2x=6
4x=12
5x=15

Answer 2

let the first number be 2x, 2nd number be 4x, 3rd number be 5x
now, sum of their cubes = 5319
so, (2x)³ + (4x)³ + (5x)³ = 5319
      8x³ + 64x³ + 125x³ =5319
      197x³ = 5319
x³ = 5319÷197 = 27
x = ³√27 = 3
first number = 2x = 2×3=6
second number = 4x = 4×3 =12
third number = 5x = 5×3 =15
hope it helps.....