SOLUTION: Please help me :) 1) You invest $18000 at 6% interest per year. Set up an exponential equation and use it to determine how much money you will have after 5 years. 2) The chemical

Question 185922: Please help me :)
1) You invest $18000 at 6% interest per year. Set up an exponential equation and use it to determine how much money you will have after 5 years.
2) The chemical element strontium has a half-life of 25 years. If 8g were present initialy, how long will it take for the amount to be reduced to 2g? Set up an exponential equation and solve algebraically.
3) Solve for x: 3^(4x-1)= 9^1/3
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
1) You invest $18000 at 6% interest per year. Set up an exponential equation
and use it to determine how much money you will have after 5 years.
:
A = 18000*(1+.06)^5
A = 18000*1.06^5
A = 18000*1.3382
A = $24,088.06
;
:
2) The chemical element strontium has a half-life of 25 years.
If 8g were present initially, how long will it take for the amount to be
reduced to 2g? Set up an exponential equation and solve algebraically.
:
t = time in yrs for this to happen
= 2
divide both sides by 8
=
= .25
Using nat logs
*ln(2) = ln(.25)
.693* = -1.386
:
Multiply both sides by 25
-.693t = -1.386 * 25
:
-.693t = -34.657
t =
t = +50.0 yrs
:
:
3) Solve for x: 3^(4x-1)= 9^1/3
Cube both sides and you have;

therefore
12x - 3 = 2
12x = 2 + 3
x =
:
:
you can check all three solutions by substitution and entering the
original equations into a good calc
RELATED QUESTIONS
I need help setting up an equation and solving it. Can you please help me? Sal has... (answered by ankor@dixie-net.com)

I need help setting up an equation for a word problem and solving it. I have to use a... (answered by TutorDelphia)

Phyllis invested 38000 dollars, a portion earning a simple interest rate of 4 percent per (answered by richwmiller)

Last year, Teresa had to invest. She invested some of it in an account that paid simple... (answered by stanbon)

Please help me solve this equation: Sue invested $10,000 in three parts. With one part... (answered by Theo)

The question is: Tina invested $600, part at 8% interest per year, and the rest at 12%... (answered by jim_thompson5910)

Ivan had $10,000 to invest. He invested some in an account that paid 7% simple interest... (answered by mananth)

Please help me understand this The formula when interest is compounded n time per year... (answered by stanbon,josmiceli)

A bank loaned out $18000, part of it at the rate of 6% per year and the rest at... (answered by ikleyn,greenestamps,MathTherapy)