How do I sum a number with only the top row of the matrix?

I have a 480 x 11 matrix of numbers (cash inflows) and need to sum a number, say negative 10, with the elements in the first row of the matrix only leaving the remaining elements unchanged. How can I sum this number (negative 10) with the original 480 x 11 matrix such that my output will be the same as the original matrix except that the numbers in the first row of the matrix will have been reduced by 10. Thanks!

Answer 1

[Sean de Wolski]

x(1,:) = x(1,:) + -10

[txvmi07]

Thank you very much!