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7 votes
If 18√8 - 8 √18 = √n, what is n?

1 Answer

11 votes

Answer:

n=288

Explanation:

Rewrite the equation as

n

=

18

8

8

18

.

n

=

18

8

8

18

To remove the radical on the left side of the equation, square both sides of the equation.

√n

2

=

(

18

8

8

18

)

2

Simplify each side of the equation.

Use

n

a

x

=

a

x

n

to rewrite

n as n

1

2

.

(

n

1

2

)

2

=

(

18

8

8

18

)

2

Simplify

(

n

1

2

)

2

.

Multiply the exponents in

(

n

1

2

)

2

.

Apply the power rule and multiply exponents,

(

a

m)n

=

a

m

n

.

n

1

2

2

=

(

18

8

8

18

)

2

Cancel the common factor of 2

Cancel the common factor.

n

1

2

2

=

(

18

8

8

18

)

2

Rewrite the expression.

n

1

=

(

18

8

8

18

)

2

Simplify.

n

=

(

18

8

8

18

)

2

Simplify

(

18

8

8

18

)

2

Simplify each term.

Rewrite

8 as 2

2

2

.

Factor

4 out of 8

n

=

(

18

4

(

2

)

8

18

)

2

Rewrite

4 as 2

2

n

=

(

18√

2

2

2

8

18

)

2

Pull terms out from under the radical.

n

=

(

18

(

2

2

)

8

18

)

2

Multiply

2 by 18

n

=

(

36

2

8

18

)

2

Rewrite

18

as

3

2

2

.

Factor

9

out of

18

.

n

=

(

36

2

8

9

(

2

)

)

2

Rewrite

9

as

3

2

.

n

=

(

36

2

8

3

2

2

)

2

Pull terms out from under the radical.

n

=

(

36

2

8

(

3

2

)

)

2

Multiply

3

by

8

.

n

=

(

36

2

24

2

)

2

Simplify terms.

Subtract

24

2

from

36

2

.

n

=

(

12

2

)

2

Simplify the expression.

Apply the product rule to

12

2

.

n

=

12

2

2

2

Raise

12

to the power of

2

.

n

=

144

2

2

Rewrite

2

2

as

2

.

Use

n

a

x

=

a

x

n

to rewrite

2

as

2

1

2

.

n

=

144

(

2

1

2

)

2

Apply the power rule and multiply exponents,

(

a

m

)

n

=

a

m

n

.

n

=

144

2

1

2

2

Combine

1

2

and

2

.

n

=

144

2

2

2

Cancel the common factor of

2

.

Cancel the common factor.

n

=

144

2

2

2

Rewrite the expression.

n

=

144

2

1

Evaluate the exponent.

n

=

144

2

Multiply

144

by

2

.

n

=

288

User Paul Freez
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