slope formula is given as:
[tex]m = \frac{y_2-y_1}{x_2-x_1}[/tex]
1.)
[tex] \frac{1}{4} = \frac{a-(-3)}{2-4} [/tex]
[tex]2-4 = 4(a+3)[/tex]
[tex]-2 = 4a + 12[/tex]
[tex]4a = -2-12[/tex]
[tex]4a = -14[/tex]
[tex]a = - \frac{14}{4} [/tex]
or
[tex]a = - \frac{7}{2} [/tex]
2.)
[tex]4 = \frac{(a-2)-5}{1-(a+3)} [/tex]
[tex]4 = \frac{a-7}{-a-2} [/tex]
[tex]4(-a-2) = a-7[/tex]
[tex]-4a - 8 = a-7[/tex]
[tex]-8 + 7 = a + 4a[/tex]
[tex]5a = -1[/tex]
[tex]a = - \frac{1}{5} [/tex]
