Answer:
Step-by-step explanation:
The summation formula ( arithmetic sequence when the first terme is : A1 = 13
and the coomo diff is d= -4
Sn = n/2(A1 +An)
An = A1+(n-1)d
An = 13 +(n-1)(-4)
An = -4n +17
Sn = n/2(13+17-4n) = n/2(30-4n)
Sn = -2n² +15n
in this exercice : n =4 S4 = -2(4)² +15(4) = -32+60 = 28
verify : 13 + 9 + 5 + 1 =28 ......right
To turn a fraction into a decimal you have to divide the numerator by the denominator. For example: 6/7 into a decimal would be 1.16666667 because 7 / 6 = <span>1.16666667
Hope I helped!
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Answer:
85 or 40 hm..................................
I think this is it :) sorry if it’s not!
<h2>Differentiation:</h2><h3><u>Pyramids:
</u></h3>
- Pyramids have base which are in triangular or square shape which connects with the base.
- Pyramids have only one base.
- In pyramids, all sides are parallel to each other and they all meet at apex.
<h3><u>Prisms:
</u></h3>
- Prisms have two ends in a geometrical structure with same structure along the length.
- Prisms are widely used in optics.
- Prisms have two bases.
- In prisms, the base and the sides are perpendicular to each other.