Zoe invest $600 in college savings account. The account earns 5.7% interest compounded quarterly. How many years will it take for Zoe's account to reach $7,000?

43.407 years

Step-by-step explanation:

Zoe invest $600 in college savings account. The account earns 5.7% interest compounded quarterly. How many years will it take for Zoe's account to reach $7,000?

We are asked to find time t in a compound interest formula

The formula is given as:

t = log(A/P) / n[log(1 + r/n)]

A = Total amount = $7000

P = Principal = $600

n = number of times interest is compounded = Quarterly =4

r = Interest rate = 5.7% = 0.057

Hence,

t = log(7000/600) /4[log (1 + 0.057/4)]

t = 43.407 years

x = ±sqrt(10)

step-by-step explanation:

5 - 2x² = -15

subtract 5 from each side

5-5 - 2x² = -15-5

-2x^2   = -20

divide by -2 on each side

-2x^2   /-2= -20/-2

x^2 =10

take the square root on each side

sqrt(x^2 )=±sqrt(10)

x = ±sqrt(10)

check:

5 - 2x² = -15

+sqrt(10)

5 - 2(sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

-sqrt(10)

5 - 2(-sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15