The explicit rule for a sequence is given.

Mathematics

2 answers:

never [62]4 years ago

7 0

Answer:

$a_{1} =\frac{2}{5}$ ,Recursive formula is :

$a_{n} =a_{n-1} .5$

Step-by-step explanation:

To find a1 we put n=1 in the given Geometric sequence :

$a_{1} =\frac{2}{5}5^{1-1}$

$a_{1} =\frac{2}{5}$

$a_{2} =\frac{2}{5}5^{2-1} = 2$

Common difference = 2÷ $\frac{2}{5}$ = 5.

r=5.

Recursive formula for a geometric sequence is

$a_{n} =a_{n-1} .r$

Recursive formula is :

$a_{n} =a_{n-1} .5$

bogdanovich [222]4 years ago

7 0

Answer: a1=2/5 and an= 5an-1

Just took the test, you're welcome

You might be interested in

X = 0.045<br> Prove algebraically that x can be written as 1/22

blagie [28]

The least decimal place in 0.045 is found in the thousandths place. Thus, if expressed as a fraction, it would be 45/1000. Let's substitute this to the equation:

x = 45/1000
1000x = 45
(1000/45)x = 1

When you divide 1000 by 45, the quotient would be 22.2222222... This could be round to the nearest whole number which is 22. Then,

22x = 1
x = 1/22

I hope I was able to answer your question. Have a good day.

7 0

4 years ago

Read 2 more answers

Please help me im stuck

dmitriy555 [2]

Answer:

a = -0.5

Step-by-step explanation:

$\rm Solve \: for \: a: \\ \rm \longrightarrow - \dfrac{1}{4}a - 4 = \dfrac{7}{4}a - 3 \\ \\ \rm Put \: each \: term \: in \: - \dfrac{1}{4}a - 4 \: over \: the \\ \rm common \: denominator \: 4: \\ \rm - \dfrac{a}{4} - 4 = - \dfrac{a}{4} - \dfrac{16}{4} : \\ \rm \longrightarrow - \dfrac{a}{4} - \dfrac{16}{4} = \dfrac{7}{4}a - 3 \\ \\ \rm - \dfrac{a}{4} - \dfrac{16}{4} = \dfrac{ - a - 16}{4} : \\ \rm \longrightarrow \dfrac{ - a - 16}{4} = \dfrac{7}{4}a - 3 \\ \\ \rm Put \: each \: term \: in \: \dfrac{7}{4}a - 3 \: over \: the \\ \rm common \: denominator \: 4: \\ \rm \dfrac{7a}{4} - 3 = \dfrac{7a}{4} - \dfrac{12}{4} : \\ \rm \longrightarrow \dfrac{ - a - 16}{4} = \dfrac{7a}{4} - \dfrac{12}{4} \\ \\ \rm \dfrac{7a}{4} - \dfrac{12}{4} = \frac{7a - 12}{4} : \\ \rm \longrightarrow \dfrac{ - a - 16}{4} = \dfrac{7a - 12}{4} \\ \\ \rm Multiply \: both \: sides \: by \: 4: \\ \rm \longrightarrow \dfrac{ - a - 16}{ \cancel{4}} \times \cancel{4}= \dfrac{7a - 12}{ \cancel{4}} \times \cancel{4} \\ \\ \rm \longrightarrow -a - 16 = 7 a - 12 \\ \\ \rm Subtract \: 7 a \: from \: both \: sides: \\ \rm \longrightarrow (-a - 7 a) - 16 = (7 a - 7 a) - 12 \\ \\ \rm -a - 7 a = -8 a: \\ \rm \longrightarrow -8 a - 16 = (7 a - 7 a) - 12 \\ \\ \rm 7 a - 7 a = 0: \\ \rm \longrightarrow -8 a - 16 = -12 \\ \\ \rm Add \: 16 \: to \: both \: sides: \\ \rm \longrightarrow (16 - 16) - 8 a = 16 - 12 \\ \\ \rm 16 - 16 = 0: \\ \rm \longrightarrow -8 a = 16 - 12 \\ \\ \rm 16 - 12 = 4: \\ \rm \longrightarrow -8 a = 4 \\ \\ \rm Divide \: both \: sides \: of \: -8 a = 4 \: by \: -8: \\ \rm \longrightarrow \dfrac{ - 8a}{ - 8} = \dfrac{4}{ - 8} \\ \\ \rm \dfrac{ - 8}{ - 8} = 1: \\ \rm \longrightarrow a = - \dfrac{4}{ 8} \\ \\ \rm - \dfrac{4}{ 8} = - \dfrac{1}{2} : \\ \rm \longrightarrow a = - \dfrac{1}{2} \\ \\ \rm \longrightarrow a = - 0.5$