Question

Which of the following is the axis of symmetry for the function?
y = 3x2 + 5x - 8
y = -5/6x
y = -5/2x
x = -5/6
x = -5/2

Answer 1

\[y=3x ^{2}+5x-8=3\left( x ^{2} +\frac{ 5 }{ 3 }x\right)-8\]
\[y=3\left( x ^{2} +\frac{ 5 }{ 3}x+\left( \frac{ 5 }{ 6 } \right)^{2}\right)- 3*\left( \frac{ 5 }{6 } \right)^{2}-8
\[y=3\left( x+\frac{ 5 }{6} \right)^{2}-\frac{ 25 }{12 }-8\] \]
\[y+\frac{ 121 }{ 12 }=3\left( x+\frac{ 5 }{ 6 } \right)^{2}\]
It is an upward parabola and axis of symmetry is
\[x=-\frac{ 5 }{6 }\]