Question

Determine o valor máximo ou mínimo das funções quadráticas dadas por:
A) f(x)=2x²+7x-4
B) h(x)= -√5x² - 5x +1

Answer 1

$y_V=\dfrac{-\Delta}{4a}$

a) $f(x)=2x^2+7x-4$

$\Delta=7^2-4\cdot2\cdot(-4)=49+32=81$

$y_V=\dfrac{-81}{4\cdot2}=\dfrac{-81}{8}$

b) $h(x)=-\sqrt{5}x^2-5x+1$

$\Delta=(-5)^2-4\cdot(-\sqrt{5})\cdot1=25+4\sqrt{5}$

$y_V=\dfrac{-25-4\sqrt{5}}{-4\sqrt{5}}\cdot\dfrac{\sqrt{5}}{\sqrt{5}}=\dfrac{-25\sqrt{5}-20}{-20}=\dfrac{5\sqrt{5}+4}{4}$