Find the sum of the geometrical equation -3 , 18 , -108 , if there are 7 terms

Hello from MrBillDoesMath!

Sum = -119,962                    ( I hope!)

Discussion:

Let's determine the pattern.

first term:  -3

2nd term:  (-3) * (-6) = 18                     (multiply first term by -6)

3rd  term:  (18) * (-6) = -108                 (multiply 2nd term by -6)

4th term :  (-108)*(-6) = 648                ( etc)

5th term :  (648)*(-6) =  -3888            (etc)

6th term :  (-3888)*(-6) = 23328         (etc)

7th term:   (23328)*(-6) =  -139967     (etc)

Sum = -119,962

A simpler way to do this is to use the formula for the sum of a geometric series to n terms. The series is

-3  Sum ( -6)^n                n = 0, 1, 2, 3, 4, 5, 6

Regards,  

MrB

P.S.  I'll be on vacation from Friday, Dec 22 to Jan 2, 2019. Have a Great New Year!

step-by-step explanation:

we are given a graph for system of inequalities.

in order to write the system of inequalities for the given graph, we need to find the inequality for each of the line separately.

let us find the slope of dotted line first.

taking two coordinates on the graph.

let us say (0,0) and (3,1).

let us find the slope of the line now.

slope of the dotted line would be =.

y-intercept of dotted line is y=0 only.

plugging slope m= and b=0 in slope-intercept form y=mx+b, we get

.

the line is shaded up of that dotted line.

therefore, for shading up we would take greater than inequality symbol > .

and because it's a dotted line we would take only > symbol in place of = sign in above equation of line.

therefore, inequality for dotted line would be

let us take two points (3,1) and (0,4) on the solid line.

slope of the solid line would be =.

for the solid line we have y-intercept b= 4.

plugging slope m= -1 and b=4 in slope-intercept form y=mx+b, we get

y = -1x + 4.

the line is shaded down of that solid line.

therefore, for shading down we would take less than inequality symbol < .

and because it's a solid line we would take ≤ symbol in place of = sign in above equation of line.

therefore, inequality for solid line would be