The sum of the square of two consecutive whole number is 25. find the numbers

Don't you mean "the sum of the squares ..."?
The sum of the squares of two consecutive whole numbers is 25.  Find the numbers.  Let the first be represented by x and the second by x+1.
Then x^2+(x+1)^2=25.  Expanding, x^2+x^2+2x+1=25.
Rewriting this as a quadratic equation in standard form,

2x^2+2x+1=25, or 2x^2+2x-24=0.  Simplifying, x^2+x-12=0.
Factoring, (x-3)(x+4)=0.  Solving for x:  x-3=0, so x=3; x+4=0, so x=-4.
Choose the positive x value:  x=3.  Then the next consecutive number is 2+1=3+1=4.

Check:  Does 3^2 + 4^2 = 5^2 = 25?  Yes.
The numbers are 3 and 4.