f(m,n)=45m+36n , where m and n are integers.What is the minimum positive value for f(m,n) for all values of m , n (this may be achieved for various values of m and n)?
5m+4n has to be an integer, and the smallest positive integer is 1. You can achieve this in many ways, one is (m = 1, n = -1).
But we need to mulitply it by 9, so our answer is 9.
I hope this helped. :))