You use the arithmetic sequence formula and input the information given to you.
tn = a + (n-1)d
t(56) is what your looking for so don't worry about the tn.
a is your first term,
a = 15.
n is the position of the term you are looking for, n = 56.
And d is the common difference, you find this by taking t2 and subtracting t1. t2=18 and t1=15.
d = 18 - 15 = 3
Inputting it all into the formula you get,
t(56) = 15 + (56-1)(3)
term 56 = 180.
You use this formula to find any term in a sequence provided you are given enough info. You can also manipulate it if you are asked to find something else like the first term(a), common difference(d) or term position(n). It just depends on what the question is asking and what information you are given. :)
Hope this helps!

7 0

3 years ago

Please can someone help me?

Debora [2.8K]

If the perimeters are equal, you can form an equation to find x:
x + x + 12 + x + x + 12 = x + 11 + x + 11 + x + 16
4x + 24 = 3x + 38
- 3x
x + 24 = 38
- 24
x = 14
Now you can substitute the x value into the perimeter:
(4 × 14) + 24
56 + 24 = 80 cm

(3 × 14) + 38
42 + 38 = 80 cm

So the perimeter would be 80 cm.
I hope this helps!

6 0

3 years ago

Use the following algorithm:

andriy [413]

Answer:

First it says that you have to multiply the number x times 2, this will give you 2x as a result. Next you have to build your equation which is 2x=10, when you have an equation like this, you divide the result with the number before x (x=10÷2) your result will be x=5. Now you have to square the result (which is x) to get y, when squaring a number you have to multiply it by itself (depending of how many times it's asking to do so when there's a small number at the upper right corner of your number, that's how many times you multiply it) so if you have to square 5, it should be 5×5 which gives you the result of y being 25.

5 0

4 years ago