Question

Find the value of c such that the expression is a perfect square trinomial

x squared plus 4x plus c

Answer 1

c = 4

Explanation:

In a perfect square trinomial, the following relationship is true:

`(x+y)^2=x^2+2xy+y^2`

In order for the given expression to be a perfect square trinomial:

`x^2=x^2\\4x=2xy\\c=y^2`

Solving for 'c':

`4x=2xy\\y=2\\c=y^2=2^2\\c=4`

Therefore, c must be equal to 4.