Question

le=" - 10 \times 18 {r}^{ - 8} = - 2" alt=" - 10 \times 18 {r}^{ - 8} = - 2" align="absmiddle" class="latex-formula">
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Answer 1

Answer:

1.107   =  r

Step-by-step explanation:

To solve this for r, do the following:

Add 10 to both sides, to isolate the r term on the left:  18r^(-8) = 8

Divide both sides by 18, to isolate r^(-8):   r^(-8) = 8/18

Invert both sides:  r^8 = 9/4

Take the natural log or both sides:

8 ln r = ln 9 - ln 4, or

8 ln r = 0.8109, so that ln r = 0.1014

to find r, raise e to the power ln r on the left and e to the power 0.1014 on the right:

  ln r           0.1014

e         =    e              =  1.107   =  r