what is the value of c so that x^2-11x+c is a perfect-square trinomial?

To find the value of c so that x^2 - 11x + c is a perfect-square trinomial, we need to find the value c that completes the square.

To complete the square, we need to take half of the coefficient of x (in this case, -11) and square it.

Half of -11 is -11/2 = -5.5

Squared, -5.5 x -5.5 = 30.25

Therefore, the perfect-square trinomial is x^2 - 11x + 30.25 where c = 30.25.