Answer:
11.4 years
Step-by-step explanation:
We assume you want to know the time it takes for Lucy's investment of $1200 to have a value of $6400. The compound interest formula is good for finding that.
FV = P(1 +r/n)^(nt)
for principal P invested at rate r per year for t years, compounded n times per year. We want to find t such that ...
6400 = 1200(1 +0.15/4)^(4t)
16/3 = 1.0375^(4t) . . . . divide by 1200
log(16/3) = 4t·log(1.0375) . . . . take logarithms
t = log(16/3)/(4·log(1.0375)) ≈ 11.4
It will take about 11.4 years for Lucy's investment value to be $6400.
Hey there!
y = -2x + 19
y = x + 7
We gonna solve this system of equation by using the substitution method.
We wanna solve y = -2x + 19 for y
Let start by substitute -2x + 19 for y in y = x + 7
y = x + 7
-2x + 19 = x + 7
Subtract x from both sides
-2x + 19 - x = x + 7 - x
-3x + 19 = 7
Now subtract 19 on both sides
-3x + 19 - 19 = 7 - 19
-3x = -12
Then divide both sides by -3
-3x/-3 = -12/-3
x = 4
We have the value of x. Now we gonna use that same value to find the value for y.
We gonna do that by substitute 4 for x in y = -2x + 19
y = -2x + 19
y = -2(4) + 19
y = -8 + 19
y = 11
Thus,
The answer is: x = 4 and y = 11
Let me know if you have questions about the answer. As always, it is my pleasure to help students like you!
