what number must be added to x^2+11x to make it a perfect square trinomial?

Answer 1

x^2+11x
=(x)^2+2.x.(11/2)
To make it a perfect sqare (11/2)^2 or 121/4 or 30 1/4 is to be added

Answer 2

x^2 + 11x

In order to make this a perfect square trinomial, the magic number you have to add is "half squared" of the coefficient of x. When I say "half squared", I mean take half of the coefficient of x (which is the same as multiplying by 1/2), and then square the resulting value.

11 * (1/2) = (11/2), squared is (121/4)

Therefore, we have to add 121/4 to make it a perfect square trinomial.

x^2 + 11x + 121/4 is a perfect square trinomial, because it factors into
(x + 11/2)(x + 11/2), or
(x + 11/2)^2

Answer 3

Take the second term, 11, take half of it, then square it.

Which means (11/2)^2 = 121/4

Answer 4

x^2 + 11x
= (x)^2 + 2 (x) (11/2) + (11/2)^2 - (11/2)^2
= (x + 11/2)^2 - 121/4

To be added >> 121/4