X^2 + x + 1 + 3x^2 + 3x + 2. Just combine the like terms:
x^2 + 3x^2 + x + 3x + 1 + 2
4x^2 + 4x + 3. <--- the sum.
Answer:
The third side must be smaller than 20 inches and greater than 4 inches

Step-by-step explanation:
Let a, b and c be the lengths of triangle's sides. Then

Use this rule in your case. So, if a=12 and b=8, then

Hence, you get

From these inequalities, you can state that

So, c must be smaller than 20 inches and greater than 4 inches.
Answer:
18
Step-by-step explanation:
I did that in my head could be wrong
Answer:
add
Step-by-step explanation:
add