How do you graph y=-(x+3)^2 + 5?

1 Answer
Dec 17, 2017

Vertex: (-3,5)

Y-intercept: (0,-4)

X-intercepts: (-3+sqrt5,0),(-3-sqrt5,0)

Approximate x-intercepts: x~~(-0.7639,0),"and"~~(-5.236,0)

Explanation:

Graph:

y=-(x+3)^2+5 is a quadratic equation in vertex form:

y=a(x-h)^2+k,

where:

a=-1, h=-3, and k=5

The vertex, (h,k), is (-3,5)

To find the y-intercept, substitute 0 for x and solve for y.

y=-1(0+3)^2+5

y=-9+5

y=-4

Y-intercept: (0,-4)

To find the x-intercepts, substitute 0 for y and solve for x.

-(x+3)^2+5=0

-(x+3)^2=-5

Divide both sides by -1.

(x+3)^2=(-5)/(-1)

Simplify.

(x+3)^2=5

Take the square root of both sides.

x+3=+-sqrt5

Subtract 3 from both sides.

x=-3+-sqrt5

X-intercepts: (-3+sqrt5,0),(-3-sqrt5,0)

x~~(-0.7639,0),"and"~~(-5.236,0)

Summary:

Vertex: (-3,5)

Y-intercept: (0,-4)

X-intercepts: (-3+sqrt5,0),(-3-sqrt5,0)

Approximate x-intercepts: x~~(-0.7639,0),"and"~~(-5.236,0)

Plot the points and sketch a parabola through the points. Do not connect the dots.

graph{y=-(x+3)^2+5 [-10, 10, -5, 5]}