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]
3 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]3 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
Write the equation of the line parallel to<br> y=-2/3x+4 and through the point (–3, 15)
MrRa [10]
Parallel = same slope
y = -2/3x + b
Plug in point
15 = -2/3(-3) + b
15 = 2 + b, b = 13
Solution: y = -2/3x + 13
6 0
3 years ago
Read 2 more answers
BRAINLIESTT
Rudik [331]

9514 1404 393

Answer:

  3 months

Step-by-step explanation:

We don't know what's on your list of "useful financial formulas." One that can be used here is the formula for simple interest:

  I = Prt . . . . . interest on principal P at annual rate r for t years

Solving for t gives ...

  t = I/(Pr)

Filling in the given values, we can find t to be ...

  t = 138/(4800×0.115) = 138/552 = 1/4

1/4 year is 3 months -- the duration of the loan.

4 0
3 years ago
The access code for a vault consists of four digits. The first digit
Vikki [24]

Answer:

5 * 10 * 10 * 9 = 4500

Step-by-step explanation:

6 0
3 years ago
Read 2 more answers
Fifty-eight boys were asked if they play football and/or baseball. Thirty-one of them said they do not play baseball. Sixteen of
Arte-miy333 [17]
The two-way table is attached.

We start out placing 31 in the Total column beside the Don't Play Baseball row.  We then place 16 in the Total row under the Play Football column.  20 goes in the Don't Play Baseball row under the Don't Play Football column.

Since there are 31 people that do not play baseball, and 20 of them don't play football, this leaves us with 31-20=11 that do not play baseball and play football.

There are 58 people total, so this goes in the Total row under the Total column.

There are 58 people, and 31 of them do not play baseball; this leaves us 58-31=27 total that play baseball.

16 total people play football, and 11 of them don't play baseball.  This leaves us 16-11=5 people that play football and play baseball.

There are 58 people, and 16 of them play football; this leaves us 58-16=42 total that don't play football.

42 people don't play football, and 20 of them don't play baseball; this leaves us 42-20=22 people that don't play football and play baseball.

5 people play baseball and play football, and 22 people play baseball and don't play football; this gives us 5+22=27 people total that play baseball.

4 0
3 years ago
Hellllllppppppppppppppppppppppppppppp
larisa [96]

Answer:

c

Step-by-step explanation:

7 0
3 years ago
Other questions:
  • Tony can grow 4 flowers with every seed packet. How many seed packets does Tony need to have in total of 16 flowers in his garde
    9·1 answer
  • Please help me with number 9
    5·1 answer
  • Which value is equivalent to [(7x3x2)/(7x5)]^2 x [(7^0)x(5^-3)]^3 x 5^-9?
    13·1 answer
  • What is the volume of a solid that 2m, 2m, 9m, 9m, 6m?
    9·1 answer
  • Solve: 10(0.5x- 2) = -3x + 20 + 8x
    11·2 answers
  • Owens Orchards sells apples in a large bag by weight. A sample of seven bags contained the following numbers of apples: 23, 19,
    15·1 answer
  • Laylaguarra bye broo
    9·1 answer
  • The number of red marbles in a jar is 3 times the number of blue marbles.
    7·2 answers
  • Write 4^6 as a power of 2.
    9·2 answers
  • You want to create a piece of pottery at an art studio. The total cost is the cost of the piece plus an hourly studio fee. The c
    14·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!