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3 years ago

An arithmetic series has seven terms. the first term is 5 and the last term is 53. find the sum of the series!

1 answer:

5 0

The easiest way is to use (& to memorize) the sum formula for a AP:

Sum = 1st term added to the last term & multiplied by half the number of terms
S = (a+l)n/2

S = (5 + 53)(7/2) = 203

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Help please and thanks! I'll award brainliest if you show your work as well :)

iren2701 [21]

Answer:

6 inches

Step-by-step explanation:

Formula for surface area of a cylinder:

$SA=2\pi r^{2} +2\pi rh$

Plug in values and solve for the radius:

$180\pi =2\pi r^{2} +2\pi r(9)\\$

Divide both sides by $2\pi$

$90=r^{2} +r(9)$

Subtract 90 from both sides

$0=r^{2} +9r-90$

Use the quadratic equation to find the roots

$x=(-b$ ± $\sqrt{b^2-4ac})*\frac{1}{2a}$ (sorry for formatting, Brainly doesn't

allow equations with ± in them)

$x=\frac{-9+\sqrt{9^2-4*1*90} }{2(1)}$ and $x=\frac{-9-\sqrt{9^2-4*1*90} }{2(1)}$

$x=\frac{(-9+\sqrt{81+360})}{2}$ and $x=\frac{(-9-\sqrt{81+360})}{2}$

$x=\frac{(-9+\sqrt{441})}{2}$ and $x=\frac{(-9-\sqrt{441})}{2}$

$x=\frac{(-9+21)}{2}$ and $x=\frac{(-9-21)}{2}$

$x=\frac{12}{2}$ and $x=\frac{-30}{2}$

$x=6$ and $x=-15$

We can't have a negative radius, so that leaves us with r=6 in.

8 0

2 years ago

Help please!!!!!!!!!!

enyata [817]

Set up a ratio

3/7 = 6/n

Then cross multiply

3n = 42

n = 14

7 0

3 years ago

Please help me out with this

adoni [48]

The numbers in the chart are -7.1, -3.4, -1.2, 2.1, and 3.4. So, from greatest to least the numbers will be:

3.4, 2.1, -1.2, -3.4, and then -7.1.

With absolute value, the numbers from greatest to least are:

|7.1|, |3.4|, 3.4, 2.1, |1.2|.

However, this is assuming that Friday is 3.4, which was given information on the last question. Hope this helps!

4 0

3 years ago

What is the sum of the 9th square number and the 3rd cube number?

Lesechka [4]

The sum of the 9th square number and 3rd cube number is 108

7 0

2 years ago

Read 2 more answers

Find the area of the triangle when the coordinates are (2.5,4.5),(2,0),(9,2)

HACTEHA [7]

The area of the triangle is 14.625.... in order to find the area of a triangle just use this formula b×h÷2

6 0

3 years ago