1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Alex_Xolod [135]
2 years ago
7

Series calcular s=1+2+3+....+86

Mathematics
1 answer:
qwelly [4]2 years ago
6 0

Answer:

S = 3741

Step-by-step explanation:

Here, we want to calculate the sum of the first 86 numbers (starting from 1)

Mathematically, we can use the formula;

Sn = n/2[ a + L]

Where n is the number of terms (86 here)

a is the first term which is 1 and L is the last term which is 86

So, we have the sum as;

Sn = 86/2(1 + 86) = 43 * 87 = 3741

You might be interested in
Leahs age is twice her cosins age. If they add thier ages together, they get 36. How old are leah and her cosin
Art [367]
Leah is 24 and her cousin is 12. Since 24 is double of 12, thats your answer and it makes the most sense.
6 0
3 years ago
Sophie Ruth is eating a
Firdavs [7]

Answer:

15 grams

Step-by-step explanation:

There is a 50 gram chocolate bar that contains 30% cocoa. So we are basically finding 30% of 50. We break 30 into 3*10 and 50 into 5*10. 5*3 = 15.

Therefore, there are 15 grams of cocoa in the chocolate bar.

I hope this helps.

6 0
2 years ago
Show that √(1-cos A/1+cos A) =cosec A - cot A​
Gennadij [26K]

Hi there!

\sqrt{\frac{1-cosA}{1+cosA}} =

We can begin by multiplying by its conjugate:

\sqrt{\frac{1-cosA}{1+cosA}} * \sqrt{\frac{1+cosA}{1+cosA}}  = \\\\\sqrt{\frac{(1-cosA)(1 + cosA)}{(1+cosA)(1 + cosA)}} =

Simplify using the identity:

1 - cos^2A = sin^2A

\sqrt{\frac{(1-cos^2A)}{(1+cosA)^2}} =\\\\\sqrt{\frac{(sin^2A)}{(1+cosA)^2}} =

Take the square root of the expression:

{\frac{sinA}{1+cosA} =

Multiply again by the conjugate to get a SINGLE term in the denominator:

{\frac{sinA}{1+cosA} * {\frac{1-cosA}{1-cosA} =\\

Simplify:

{\frac{sinA(1-cosA)}{1-cos^2A} =

Use the above trig identity one more:

{\frac{sinA(1-cosA)}{sin^2A} =

Cancel out sinA:

{\frac{(1-cosA)}{sinA}  =

Split the fraction into two:

{\frac{1}{sinA}   - \frac{cosA}{sinA} =

Recall:

1/sinA = cscA\\\\cosA/sinA = cotA

Simplify:

\frac{1}{sinA} + \frac{cosA}{sinA} = \boxed{cscA - cotA}

5 0
2 years ago
What is the result of substituting for y in the bottom equation?
jeka57 [31]
The answer is the option A, which is: A. x-7=x²+2x-4
 The explanation is shown below:
To solve this problem you must apply the proccedure shown below:
 1. You have the following system equations given in the problem above:
 <span>y=x-7
 y=x²+2x-4
2. Therefore, when you substitute for y in the bottom equation, you obtain:
 </span>x-7=x²+2x-4
8 0
3 years ago
Read 2 more answers
What is the total cost of a pair of jeans that are priced $40.00 if there is a 6.5% sales tax? $40.65 $42.60 $44.00 $46.50
-Dominant- [34]
A pair of jeans = $40.00
There is a 6.5% sales tax.

First change the % into a decimal by moving the decimal point two spaces to the left.
0.065

Multiply that by 40.00 to find out how much the tax is.

40 × 0.065 = 2.6

Now add the tax to the initial price.
40.00 + 2.6 = 42.60

The total cost is $42.60.
8 0
2 years ago
Read 2 more answers
Other questions:
  • Livia eats a chicken drumstick with 11 grams of protein. She also eats x cheese sticks, each with 7 grams of protein. The table
    5·1 answer
  • What is the common ratio and explicit formula for -2,6,-18,54?
    11·1 answer
  • Find the value of X <br><br> A: 7<br> B: -7, 7<br> C: 49<br> D: -49, 49
    12·1 answer
  • Find x in picture below. <br>a. 4 <br>b. 6 <br>c.12
    9·1 answer
  • Hi! I found the vertex for this problem, but how would I find the rest of the equation?
    13·1 answer
  • What is 3/4. ÷ 1/6 ​
    7·2 answers
  • Yr is the circundcenter of ASTU, find each measures.
    8·2 answers
  • Help? part a:
    5·2 answers
  • FREE5POINTS+THANKS+GOTTA ANSWER A SIMPLE QUESTION. What's your zodiac sign? owo
    10·2 answers
  • 20men working 8hours a day took 18days to complete a work . How long will 24 men working 5 hours a day take to complete the some
    7·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!