Question

2.Solve the following quadratic equations i. 9x^2 - 1/16 ii. 2h^2 - 3h - 27

Answer 1

$i)~9x^2-\dfrac{1}{16}=0\iff9x^2=\dfrac{1}{16}\iff x^2=\dfrac{1}{9\cdot16}\iff \\\\x^2=\dfrac{1}{144}\iff x=\pm\sqrt{\dfrac{1}{144}}=\pm\dfrac{1}{12}\Longrightarrow\boxed{x=\pm\dfrac{1}{12}}$


$ii)~2h^2-3h-27=0\\\\\Delta=b^2-4ac\to \Delta=(-3)^2-4\cdot2\cdot(-27)\to\Delta=9+216=225\\\\ \Longrightarrow h=\dfrac{-b\pm\sqrt{\Delta}}{2a}=\dfrac{-(-3)\pm\sqrt{225}}{2\cdot2}=\dfrac{3\pm15}{4}\\\\\begin{cases}h_1=\dfrac{3+15}{4}=\dfrac{18}{4}\iff \boxed{h_1=\dfrac{9}{2}}\\h_2=\dfrac{3-15}{4}=\dfrac{-12}{4}\iff\boxed{h_2=-3}\end{cases}$