If $x$ is the first number in the progression, and $r$ is the common ratio between consecutive terms, then the first four terms in the progression are

$\{x,xr,xr^2,xr^3\}$

We want to have

$\begin{cases}xr^2-x=12\\xr^3-xr=36\end{cases}$

In the second equation, we have

$xr^3-xr=xr(r^2-1)=36$

and in the first, we have

$xr^2-x=x(r^2-1)=12$

Substituting this into the second equation, we find

$xr(r^2-1)=12r=36\implies r=3$

So now we have

$\begin{cases}9x-x=12\\27x-3x=36\end{cases}\implies x=\dfrac32$

Then the four numbers are

$\left\{\dfrac32,\dfrac92,\dfrac{27}2,\dfrac{81}2\right\}$

4 0

3 years ago

Step by step explanation thanks

Inessa [10]

Answer:

C= 7y +150

850

250

Step-by-step explanation:

The cost is 7 times y, the number of yearbooks, plus 150, the upfront cost.

7 times 100 is 700, plus 150 is 850.

1900-150 is 1750 divided by 7 is 250

7 0

3 years ago

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