Question

Determine as raízes das funções
a) y= x2-9
b) y= x2+5x
c) y= x2+2x-15
d) y= x2+3x-18
* obs o dois é elevado, mas não consegui diminuir ele.

Answer 1

$\\c) y= x^2+2x-15 \\ y=\frac{-b+- \sqrt{(b^2-4ac}}{2a} \\ y=\frac{-2+- \sqrt{(2^2-4.1.(-15))}}{2.1} \\y= \frac{-2+- \sqrt{64}}{2} = \left \{ {{y'= \frac{-2+8}{2} = 3 } \atop {y''= \frac{-2-8}{2}=-5 }} \right. \\ \\ \\d) y= x^2+3x-18 \\ y=\frac{-b+- \sqrt{(b^2-4ac)}}{2a} \\y=\frac{-3+- \sqrt{(3^2-4.1.(-18))}}{2.1} \\y=\frac{-3+- \sqrt{(81)}}{2}= \left \{ {{y'= \frac{-3+9}{2}=3 } \atop {y''= \frac{-3-9}{2}=-6 }} \right.$$a) y= x^2-9 \\ y=\frac{-b+- \sqrt{(b^2-4ac}}{2a} \\y=\frac{-0+- \sqrt{(0^2-4.1.(-9)}}{2.1} \\y=\frac{0+- \sqrt{36}}{2} \left \{ {{y'= \frac{0+6}2} = 3 } \atop {y''= \frac{0-6}2} = -3 }} \right. \\ \\b) y=x^2+5x \\ y=\frac{-b+- \sqrt{(b^2-4ac}}{2a} \\y=\frac{-5+- \sqrt{(5^2-4.1.0}}{2.1} \\y=\frac{-5+- \sqrt{25}}{2} \left \{ {{y'= \frac{-5+5}{2}=0 } \atop {x= \frac{-5-5}{2}=-5 }} \right.$