Question

If 18√8 - 8 √18 = √n, what is n?

Answer 1

Answer:

n=288

Step-by-step 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