What number should be added to the expression x2 + 4x to change it into a perfect square trinomial?
A polynomial that has only three terms is called a trinomial. It is in the form of x2 + zx + 1.
Answer: The number 4 should be added to the expression x2 + 4x to change it into a perfect square trinomial.
Let's find the number.
As per the question, b = coefficient of x, a = coefficient of x2 and c = constant term.
⇒ b2 - 4ac = 0
⇒ b2 = 4ac
⇒ (4)2 = 4 (1) c
⇒ 16 = 4 × c
By dividing both the sides by 4, we get
⇒ c = 4