For this question it opens upwards in
        
             
        
        
        
For any equation,

assume solution of a form, 
Which leads to,

Simplify to,

Then find solutions,

For non repeated real root y, we have a form of,

Following up,
For two non repeated complex roots 
 where,

and,
 
the general solution has a form of,

Or in this case,

Now we just refine and get,

Hope this helps.
r3t40
 
        
             
        
        
        
A triangle is a polygon with three edges and three vertices. It is one of the basic shapes in geometry. A triangle with vertices A, B, and C is denoted.<span>A </span>triangle<span> with all sides equal is called equilateral, a</span>triangle<span> with two sides equal is called isosceles, and a</span>triangle<span> with all sides a different length is called scalene.</span>
        
                    
             
        
        
        
Answer:
2x+12=180°
Step-by-step explanation:
because linear is equal to 180°