Fill in the blank with a number to make the expression a perfect square.
U^2 + 2u + ?

Answer:
u² + 2u + 1
Step-by-step explanation:
In the question it's asking to find the the number in the blank to make the expression a perfect square.
Let the number in the blank be 'x'.
To guess 'x' , use the algebraic identity :- [tex](a + b)^2 = a^2 + (2 \times a \times b) + b^2[/tex]
While matching the expression with identity , the expression will look like this :- u² + 2ux + x²
In the expression given in the question , it's "2u" but after matching the expression with identity , it is found to be "2ux".
⇒ x = 1 (∵ If x will be 1 , then 2ux = 2×u×1 = 2u)
⇒ x² = 1
∴ The number in the blank is 1.