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
Liono4ka [1.6K]
3 years ago
15

What is sn for the arithmetic series with a1=3 an=-38 and n=8?

Mathematics
1 answer:
otez555 [7]3 years ago
4 0
Sn = n/2 (a1+an)
= 8/2 (3-38)
= 4 (-35)
= -140
You might be interested in
If alpha and beta are the zeroes of the polynomial 6x2+x-2 find the value og alpha/beta + beta/alpha
castortr0y [4]
6x^2+x-2=6x^2+4x-3x-2=2x(3x+2)-1(3x+2)\\\\=(3x+2)(2x-1)\\\\3x+2=0\to x=-\frac{2}{3}\\\\2x-1=0\to x=\frac{1}{2}\\\\\alpha=-\frac{2}{3};\ \beta=\frac{1}{2}\\\\\frac{\alpha}{\beta}+\frac{\beta}{\alpha}=\frac{-\frac{2}{3}}{\frac{1}{2}}+\frac{\frac{1}{2}}{-\frac{2}{3}}=-\frac{2}{3}\cdot\frac{2}{1}-\frac{1}{2}\cdot\frac{3}{2}=-\frac{4}{3}-\frac{3}{4}\\\\=-\frac{16}{12}-\frac{9}{12}=-\frac{25}{12}=-2\frac{1}{12}


use\ Vieta's\ formula:\\\\\frac{\alpha}{\beta}+\frac{\beta}{\alpha}=\frac{\alpha^2+\beta^2}{\alpha\beta}=\frac{\alpha^2+2\alpha\beta+\beta^2-2\alpha\beta}{\alpha\beta}=\frac{(\alpha+\beta)^2-2\alpha\beta}{\alpha\beta}=\frac{(\alpha+\beta)^2}{\alpha\beta}-2\\\\\alpha+\beta=\frac{-b}{a};\ \alpha\beta=\frac{c}{a}\\\\\frac{(\alpha+\beta)^2}{\alpha\beta}-2=\frac{\left(\frac{-b}{a}\right)^2}{\frac{c}{a}}-2=\frac{b^2}{a^2}\cdot\frac{a}{c}-2=\frac{b^2}{ac}-2

6x^2+x-2\\\\a=6;\ b=1;\ c=-2\\\\\frac{\alpha}{\beta}+\frac{\beta}{\alpha}=\frac{1^2}{6\cdot(-2)}-2=\frac{1}{-12}-2=-2\frac{1}{12}
7 0
3 years ago
Robert has 17 lb of grain he would like to put into sacks. Each sack will hold three pounds. How many sacks will he need?
satela [25.4K]

Answer:

6

Step-by-step explanation:

17/3=5.67

since you can't have 0.67 sack. you just round it up to 6

5 0
2 years ago
Read 2 more answers
Help plz I need to solve this ​
tankabanditka [31]

Answer:

2,5

Step-by-step explanation:

5 0
2 years ago
Read 2 more answers
Which hourly interval had the least rate of change?
frutty [35]

Answer:

hour 3 to hour 4

Step-by-step explanation:

that is where the slope is the least steep

7 0
2 years ago
Read 2 more answers
The formula for the equation describing a straight line is y = b0 + b1x. the value for b1 in this equation represents the ______
Rasek [7]
Equation of a straight line is normally in the form: y = mx + c.

Where, m and c are constants in which;
m = gradient
c = y-intercept.

Comparing this standard way way of writing the equation of a straight line with the current scenario, this equation can be rewritten as;
y = b1x + b0.

This way, b1 = gradient of the line while b0 = y-intercept.
4 0
3 years ago
Other questions:
  • Find the greatest common factor of 45m and 6m^5
    13·1 answer
  • The ratio of male to female is 5 to 3. if there are 400 males, how many female are there?
    15·1 answer
  • Could I get help with number 19 please
    14·1 answer
  • Eight students were asked how many books they read last summer. Their answers are listed below.
    9·2 answers
  • 5.solve for x. 6.solve for x.
    6·1 answer
  • Please answer these 3 questions there easy 30 points and brainliest.
    7·1 answer
  • Line a: 3y - x= 6
    11·1 answer
  • Plz help me well mark brainliest!
    8·2 answers
  • i'm just giving em away! Brainly, A sphere has a volume of 2,304\p mm^3. Find the diameter of the sphere.
    8·1 answer
  • QUICK PLEASE Which expression is equivalent to 45−20s ? 25−s B 5(9−4s) C s(45−20) D 5s(9−4)
    15·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!