Please help!!
brainiest = + 25 if you can answer this correctly!

If f(1)=7 and f(n)=-3f (n-1) then find the value of f(4)

f(4) = -189

Step-by-step explanation:

f(1) = 7

f(n) = -3f(n-1)

f(2) = -3f(1) = -3 × 7 = -21

f(3) = -3f(2) = -3 × -21 = 63

f(4) = -3f(3) = -3 × 63 = -189

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