Question

How to find value of y and z here

Answer 1

Here is the solution :

To find x, Adding all the numbers isn't good There is a formula we know, That is sum of numbers from 1 to n is n(n+1)/2,

Similarly We have formulas for Sum of Squares and sum of cubes !.

(1) Sum of Squares = [(n)(n+1)(2n+1)/6]
(2) Sum of cubes = [(n)²(n+1)²/4]

Now,

Here comes your answer :

To find value of y, We need to do the following :

[(30)(31)(61)/6] - [(15)(16)(31)/6]

i.e Sum of 30 squares - Sum of 15 squares !.

To find z, We need to the following :

[(50)²(51)²/4] - [(30)²(31)²/4]

I.e Sum of 50 cubes - sum of 31 cubes !.

If you don't believe the formula, Check it out by Keeping in values !

Hope you understand, Have a Great day :),
Thanking you, Bunti 360 !..