Find the value of c that completes the square

x^2-34x+c

To complete the square for the expression x^2-34x+c, we need to add the square of half the coefficient of x to the expression.

The coefficient of x is -34, so half of it is -34/2 = -17.

To find the square of -17, we calculate (-17)^2 = 289.

Adding 289 to the expression x^2-34x, we have:
x^2-34x+289+c

Therefore, the value of c that completes the square is 289.