An isotope decays at a rate of -0.0049% per year. Find the half life. (show the work)

  14,146 years

Step-by-step explanation:

The annual multiplier is (1 -0.0049%) = 0.999951. We want to find the number of times this needs to be multiplied to make the product 1/2.

  0.5 = 0.999951^t

  log(0.5) = t·log(0.999951)

  log(0.5)/log(0.999951) = t ≈ 14,145.514

The half-life is about 14,146 years.

37/3

step-by-step explanation:

step 1: simplify both sides of the equation.

7x+8(x+

1

4

)=3(6x−9)−8

7x+(8)(x)+(8)(

1

4

)=(3)(6x)+(3)(−9)+−8(distribute)

7x+8x+2=18x+−27+−8

(7x+8x)+(2)=(18x)+(−27+−8)(combine like terms)

15x+2=18x+−35

15x+2=18x−35

tep 2: subtract 18x from both sides.

15x+2−18x=18x−35−18x

−3x+2=−35

step 3: subtract 2 from both sides.

−3x+2−2=−35−2

−3x=−37

step 4: divide both sides by -3.

−3x

−3

=

−37

−3

x=

37

3