Question 65886
<pre><font size = 5><b>That's too much to post.  I'll do only the third one

Solve for x: x^2 + 4x + 7 = 0. If the solutions 
are complex numbers, then give your solutions in
the usual a + bi form. 

                    x² + 4x + 7 = 0

Use the quadratic formula:
                  ______ 
            -b ± <font face = "symbol">Ö</font>b²-4ac
        x = —————————————
                2a 

where a = 1; b = 4; c = 7

                     ____________ 
             -(4) ± <font face = "symbol">Ö</font>(4)²-4(1)(7)
        x = ———————————————————————
                     2(1) 
                   _____ 
             -4 ± <font face = "symbol">Ö</font>16-28
        x = —————————————
                 2

                   ___ 
             -4 ± <font face = "symbol">Ö</font>-12
        x = ———————————
                 2

                    __ 
             -4 ± i<font face = "symbol">Ö</font>12
        x = ——————————
                2 

                    ___ 
             -4 ± i<font face = "symbol">Ö</font>4·3
        x = ———————————
                 2 

                     _
             -4 ± 2i<font face = "symbol">Ö</font>3
        x = —————————
                2

                       _
             -4     2i<font face = "symbol">Ö</font>3
        x = ———— ± ——————
              2      2
                  _
        x = -2 ± <font face = "symbol">Ö</font>3 i 
                               
Edwin</pre>