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4 years ago

Find the explicit formula for the sequence? -1,4,-16,64......

Mathematics

1 answer:

Ede4ka [16]4 years ago

5 0

The explicit formula for given sequence is: $a_n = -1 . (-4)^{n-1}$

Step-by-step explanation:

Given sequence is:

-1,4,-16,64.....

We can see that there is no same difference between consecutive terms so we will find common ratio to see if it is a geometric sequence.

Here

$a_1 = -1\\a_2 = 4\\a_3 = -16\\a_4 = 64\\r = \frac{a_2}{a_1} = \frac{4}{-1} = -4\\r = \frac{a_3}{a_2} = \frac{-16}{4} = -4$

The explicit formula for geometric sequence is:

$a_n = a_1r^{n-1}$

Putting the values of r and a1

$a_n = -1 . (-4)^{n-1}$

Hence

The explicit formula for given sequence is: $a_n = -1 . (-4)^{n-1}$

Keywords: Geometric sequence, common ratio

Learn more about geometric sequence at:

#learnwithBrainly

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kakasveta [241]

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3 years ago

Determine if the equation below is a function with independent variable x. If so, find the domain. If not, find a value of x to

Andre45 [30]

Answer:

No because it contains points (3,4) and (3,-4). You cannot have a x assigned to more than one y-value if you want it to be a function.

Step-by-step explanation:

A function has one output per input.

If we are trying to determine if the given is a function of x, then x is the input.

However I can get two outputs from plugging in x=3.

$3^2+y^2=25$

$9+y^2=25$

Subtract 9 on both sides:

$y^2=25-9$

$y^2=16$

Take the square root of both sides:

$y=\pm \sqrt{16}$

$y=\pm 4$ .

So input x=3 yields y=4 and y=-4.

Since this input has more than one output then the given is not a function of x.

----Also!

If you graph the equation, it is a circle with radius 5 and center (0,0). So I could I plug in any number for x between -5 and 5 excluding -5 and 5 which would yield only one output each. Since plugging in either one gives:

$(\pm 5)^2+y^2=25$