If the 4th and 7th terms of a G. P are −1/2 and
− 4, respectively, then find G5 and S6 .

G5 = -1

S6 = -63/16

Step-by-step explanation:

The formula for finding the nth term of a GP is Tn = ar^n-1

a is the first term

r is the common ratio

n is the number of terms

If the 4th term is -1/2

T4 = ar^4-1

T4 = ar³ = -1/2 1

If the 7th term is -4

T7 = ar^7-1

T7 = ar^6 = -4 2

Divide both equation

ar^6/ar³ = -4/(-1/2)

r³ = -4×-2

r³ = 8

r = 2

Common ratio is 2

Since ar³ = -1/2

a(2)³ = -1/2

8a = -1/2

a = -1/16

The first term is -1/16

Get the fifth term G5

G5 = ar⁴

G5 = (-1/16)(2)⁴

G5 = (-1/16)(16)

G5 = -1

Get the sum of the first six terms S6

S6 = a(r^n-1)/r-1

S6 = -1/16(2^6-1)/2-1

S6 = -1/16(64-1)

S6 = -63/16

Hence the sum of the first six terms is -63/16

18 units²

step-by-step explanation:

first let's find altitude bd using the distance formula

d = √((y₂ - y₁)² + (x₂ - x₁)²)

bd = √((0 - -3)² + (0 - 3)²)

bd = √18

given the placement of points a and c, we can denote that point d bisects segment ac.

we will call ac the base.

using the distance formula

ac = √((0 - 6)² + (-6 - 0)²)

ac = √72

knowing our base and our height, we can plug these into our triangle area formula

area = (b * h)/2

area = (√18 * √72) / 2

area = (√1296) / 2

area = 36 / 2

area = 18 units²