4=2.5a10

Rewrite the equation as 2.5a10=4.

2.5a10=4

Divide each term in 2.5a10=4 by 2.5.

2.5a102.5=42.5

Cancel the common factor of 2.5.

a10=42.5

Divide 4 by 2.5.

a10=1.6

a10=1.6

Take the 10th root of both sides of the equation to eliminate the exponent on the left side.

a=±1.610

First, use the positive value of the ± to find the first solution.

a=1.610

Next, use the negative value of the ± to find the second solution.

a=-1.610

The complete solution is the result of both the positive and negative portions of the solution.

a=1.610,-1.610

a=1.610,-1.610

The result can be shown in multiple forms.

Exact Form:

a=1.610,-1.610

Decimal Form:

a=1.04812238…,-1.04812238…

Solve for a 4=2.5a^10