Question

what would be the increasing and decreasing intervals of the equation y= 1/3x(squared)+4x+12

Answer 1

is this calculus or algebra...?

Answer 2

This is from my trigonometry class (algebra)

Answer 3

A simple method is to decide

is the parabola concave up or concave down

Concave up
decreasing to the left of the vertex
increasing to the right of the vertex

Concave Down

increasing to the left og the vertex
decreasing to the right of the vertex.

so you need to find the x value in the vertex...

use the line of symmetry

for a parabola \[y=ax^2 + bx + c\]

the line of symmetry is\[x = \frac{-b}{2 \times a}\]

you have b = 4 and a = 1/3

substitute them to find the line of symmetry

Answer 4

OK thanks!