IXL - Solve quadratic equations: word problems (Algebra 2 practice)

The volume of a rectangular prism is 4,860 cubic centimeters. Its length is 20 centimeters, and its height is 3 times its width.

Which equation can you use to find the width of the rectangular prism,

4,860

How wide and tall is the prism?

centimeters wide and centimeters tall

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Learn with an example

question

In the middle of math class, Max's pencil rolls off of his desk and onto the ground 2.5 feet below.

Which equation can you use to find how many seconds it takes for the pencil to hit the ground?

If an object falls from

feet above the ground, the object's height in feet,

after

seconds can be modeled by the formula

–

2.5

–

2.5

To the nearest tenth of a second, how long does it take for the pencil to hit the ground?

seconds

solution

To find how long it takes for the pencil to hit the ground, first write an equation. The formula below can be used to model the pencil's height in feet,

seconds after it falls from a height of

feet.

–

The pencil falls from a height of 2.5 feet, so

2.5

You want to find how many seconds it takes for the pencil to fall to the ground, or when it has a height of 0 feet, so

The number of seconds,

is the variable.

–

2.5

Now, solve for

Since the equation doesn't have a

-term,

you can solve for

by isolating

and then taking the square root of both sides.

–

2.5

–

2.5

–

2.5

–

2.5

±0.3952…

Since

is an amount of time, it must be positive. So, to the nearest tenth, it takes 0.4 seconds for the pencil to hit the ground.

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Teacher tools

Work it out

Not feeling ready yet? These can help:

O.6Solve a quadratic equation using the quadratic formula

O.3Solve a quadratic equation by factoring

Z.1Solve a quadratic equation using square roots

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