Simple interest on certain principle is 1/5 of the amount in 5 yrs find rate.

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9514 1404 393

  4%

Step-by-step explanation:

The simple interest formula can be used.

  I = Prt

where r is the annual rate and t is the number of years.

 1/5 = 1·r·5

 (1/5)/5 = r = 1/25 · 100% = 4%

The rate is 4%.

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

a = 3.14

b = 18

c = 18/5 or 3.6 or 3 3/5

step-by-step explanation: