# If three arithmetic means are inserted between -15 and 9,find the first of these arithmetic means.

2
by eat

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2015-09-06T15:53:38+08:00

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Add -15 and 9, then divide by 2.

The result is -6/2 = -3

-15, ____, -3, _____, 9

Add -15 and -3, then divide by 2

The result is -18/2 = -9

The common difference:
-9 - (-15) = -9 + 15 = 6

So, add 6 to -15, =-9
add 6 to -9 =  -3
add 6 to -3 = 3

These are the three missing terms between  -15 and 9.

-15, -9, -3, 3, 9

The first of the arithmetic means is -9.

2015-09-06T16:21:19+08:00

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Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
Hmmmm.

-15 _ _ _ 9
There are 5 numbers
First you will find the d or the common difference
The formula is
An=A1 + (n-1)d
A5= -15 + (5-1)d
9 = -15 + 4d
9+15 =4d
24=4d
Divided both by 4
6 = d