The fourth term in an arithmetic sequence is 18 and the seventh term is 39. If the first term is a1 , which is an equation for the nth term of this sequence?

Step-by-step explanation:

The nth term:  

So:

    a₄ = a₁ + 3d

18 =  a₁ + 3d   ⇒   3d =  18 - a₁

    a₇ = a₁ + 6d

39 = a₁ + 6d

39 = a₁ + 2(18 - a₁)

39 = a₁ + 36 - 2a₁

39 = 36 - a₁

a₁ = -3

3d = 18 - (-3)

3d = 21

d = 7

So the nth term:

d. millimeters per hour.

step-by-step explanation:

we are given that,

carlo used a rain gauge to measure the amount of water his lawn is receiving from the sprinklers.

since, according to the options, we see that,

water cannot be measured by 'miles per hour', 'meters per second' and 'grams per seconds'.

we get that, the water can be measured by 'millimeters per hour'.

hence, the appropriate rate for describing the amount of water is 'millimeters per hour'.

the answer is c)8

step-by-step explanaction: