x² + 8x + 7 = 0

Use the quadratic formula:
                  ______ 
            -b ± Öb²-4ac
        x = —————————————
                2a 

where a = 1; b = 8; c = 7

                     ____________
             -(8) ± Ö(8)²-4(1)(7)
        x = ——————————————————————
                     2(1) 
                   _____ 
             -8 ± Ö64-28
        x = —————————————
                  2

                   __ 
             -8 ± Ö36
        x = ———————————
                 2 

                    
             -8 ± 6
        x = ————————
                2 
      
                      
             -8     6
        x = ———— ± ———
              2     2
                  
        x = -4 ± 3 
                       
Using the +, x = -4 + 3, which
is one solution and equals -1
                        
Using the -, x = -4 - 3, which
is the other solution and equals -7.

Edwin