IXL - Solve equations with sums and differences of cubes (Precalculus practice)

Solve for

–

Write your answers in simplified, rationalized form.

ref_doc_title.

Learn with an example

question

Solve for

–

Write your answers in simplified, rationalized form.

key idea

Sum of cubes:

(

)

(

–

)

Difference of cubes:

–

(

–

)

(

)

solution

Notice that the expression

–

is a difference of cubes. So, you can factor it to begin solving the equation.

–

(

–

)

(

)

Factor as a difference of cubes

(

–

)

(

)

Set the linear factor equal to zero.

–

Then, set the quadratic factor equal to zero.

Quadratic formula

–

(

)

(

)

–

(

)

(

)

(

)

Quadratic formula

–

Square root of a negative number

–

𝑖

Square root of a negative number

–

𝑖

So, the equation has three solutions:

–

𝑖

and

–

𝑖

Looking for more? Try this:

$Confetti$

Excellent!

Now entering the Challenge Zone—are you ready?

Questions
answeredQuestions

Time
elapsedTime

hr	min	sec
00	00	04

SmartScore
out of 100
IXL's SmartScore is a dynamic measure of progress towards mastery, rather than a percentage grade. It tracks your skill level as you tackle progressively more difficult questions. Consistently answer questions correctly to reach excellence (90), or conquer the Challenge Zone to achieve mastery (100)! Learn more

Teacher tools

Work it out

Not feeling ready yet? These can help:

E.5Factor sums and differences of cubes

D.8Solve a quadratic equation using the quadratic formula

K.1Introduction to complex numbers

Excellent! You got that right!

Jumping to level 1 of 1

Excellent!