Answer:
[tex]1) = - \frac{d {}^{4} }{4c {}^{2} } [/tex]
[tex]2) = 2z {}^{2} [/tex]
[tex]3) = \frac{2}{3} [/tex]
[tex]4) = y - z[/tex]
[tex]5) = \frac{y}{y + 7} [/tex]
