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
iren [92.7K]
4 years ago
8

Find a_1 and d for an arithmetic sequence with these terms. a_4=9and a_7=18

Mathematics
1 answer:
jonny [76]4 years ago
3 0
\bf \begin{array}{llll}
term&value\\
-----&-----\\
a_4&9\\
a_5&9+d\\
a_6&(9+d)+d\\
&9+2d\\
a_7&(9+2d)+d\\
&9+3d=\underline{18}
\end{array}\\\\
-------------------------------\\\\
9+3d=18\implies 3d=9\implies d=\cfrac{9}{3}\implies \boxed{d=3}

\bf n^{th}\textit{ term of an arithmetic sequence}\\\\
a_n=a_1+(n-1)d\qquad 
\begin{cases}
n=n^{th}\ term\\
a_1=\textit{first term's value}\\
d=\textit{common difference}\\
----------\\
n=7\\
d=3
\end{cases}
\\\\\\
a_7=a_1+(7-1)d\implies 18=a_1+(7-1)3\implies 18=a_1+18
\\\\\\
18-18=a_1\implies \boxed{0=a_1}
You might be interested in
The ages of Jamal, Wesley, an John are consecutive integers.the sum of thier ages is 108.what are thier ages .
hodyreva [135]

Answer:

Step-by-step explanation:

We have three people

jamal = x (since im guessing hes the youngest)

wesley= x+1

John= x+2

the formula you would use is x+x+1+x+2=108

when you simplify that you get 3X+3=108

you subtract the 3 from 108 which leaves you with 3X=105

divide that by 3 which makes x=35

so

jamal is 35

wesley is 36

john is 37

3 0
3 years ago
PLEASE PLEASE HELP!!!
natka813 [3]

Answer:

398,765 books were sold

Step-by-step explanation:

How to get the answer:

1) Identify the given

  32,300 is percentage

  8.1 % is rate

  base (b) is missing

2) Solve

   b= p/r

   b= 32,300 / 8.1% or 0.081

   b= 398,765

3) Check

   398,765 x 8.1% = 32,299.97 or 32,300

5 0
3 years ago
What is the opposite of the opposite of -1.4?What is the opposite of the opposite of -1.4?
Rama09 [41]

Answer:

1.4

Step-by-step explanation:

영어를 잘 못해서 한국말hhhhhhgjfjtjrjjt

3 0
2 years ago
Read 2 more answers
Can someone help with the incorrect problems?
uranmaximum [27]

Answer:

<em>Good luck!</em>

Step-by-step explanation:

.

6 0
3 years ago
What is the simplified form of each expression?<br><br> 7x^–8 × 6x^3
klio [65]
7*6*x^-8*x^3     
42x^-8+3                    (bases same powers add)
42x^-5
1/42x^5
<span>so the simplified </span>form<span> of 7x^-8*6x^3 is=1/42x^5</span>
7 0
3 years ago
Other questions:
  • If dh = 3x -3 and fh = x+7, find the value of x for which defg must be a parallelogram.
    10·2 answers
  • 114.9 million U.S. households owned at least one TV set. Of these households, 88% received basic cable. How many households owne
    5·1 answer
  • A printer can print 25 pages per minute. At this rate, how long will it take to print 2,000 pages?
    11·2 answers
  • Find the length and show work. (100pts)
    6·2 answers
  • Which is less? 8 1/8 or 8.08
    15·2 answers
  • Two small questions...
    6·1 answer
  • Bought computer for $500. Marked down $50. Plus a 25% discount off original price. What is the original price?
    12·2 answers
  • Y=-5/2x-3 find the slope. plz I need it now
    6·2 answers
  • Write the decimal and fraction in simplest form to represent the shaded portion of
    14·1 answer
  • What's 41/7 as a Fraction greater than one?
    6·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!