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3 years ago

What is the value of r for 21-23

Mathematics

1 answer:

VladimirAG [237]3 years ago

5 0

Step-by-step explanation:

the answer is 9=3;/5

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Which of the following is true about the expression square root of 3 times square root of 2

dmitriy555 [2]

That it equals2.449 i did the math and that is what i got

7 0

3 years ago

Work out the formula of the nth term in the following quadratic sequence:<br> 19, 15, 9, 1...

Butoxors [25]

In a quadratic sequence we'll get a linear first difference and a constant second difference. Let's verify that.

n 1 2 3 4

f(n) 19 15 9 1

1st diff -4 -6 -8

2nd diff 2 2

We see that we got a constant second difference. We could just extend that and work back up to get more values.

n 1 2 3 4 5 6 7

f(n) 19 15 9 1 -9 -21 -35

1st diff -4 -6 -8 -10 -12 -14

2nd diff 2 2 2 2 2

That's just an aside; we're after the general formula. We have

f(1)=19, f(2)=15, f(3)=9

In general we can assume

f(n) = an² + bn + c

We get three equations in three unknowns,

19 = a(1²)+b(1)+c = a+b+c

15 = a(2²) + b(2) + c = 4a + 2b + c

9 = a(3²) + b(3) + c = 9a + 3b + c

That's a 3x3 linear system; it's easy to solve directly. Subtracting pairs,

4 = -3a - b

6 = -5a - b

Subtracting those,

-2 = 2a

a = -1

b = -3a -4 = -1

c = 19-a-b = 21

Answer: f(n) = -n² - n + 21

Check:

f(1) = -1 - 1 + 21 = 19, good

f(2) = -4 - 2 + 21 = 15, good

f(3) = -9 - 3 + 21 = 9, good

f(4) = -16 - 4 + 21 = 1, good

Let's check our extended table, how about

f(7)= -49 - 7 + 21 = -35, good

6 0

3 years ago

The price of a 6-minute phone call is 1.80. What is the price of a 12-minute phone call?

hoa [83]

Answer:

3.60

Step-by-step explanation:

1.80 x 2

4 0

3 years ago

Read 2 more answers

Find the circumference of a circle that has a 25-inch radius. Use 3.14 to approximate π.

Sergio [31]

$\huge \tt \color{pink}{A}\color{blue}{n}\color{red}{s}\color{green}{w}\color{grey}{e}\color{purple}{r }$

$\large\underline{ \boxed{ \sf{✰\:Important\: point's }}}$

➣ Circle:- A two-dimensional geometric figure, a line, consisting of the set of all those points in a plane that are equally distant from a given point (center).
➣ Circumference:- The line that bounds a circle or other two-dimensional figure

${ \rule{70mm}{2.9pt}}$

★ also circumference of a circle is also known as it's perimeter

➣To find circumference of circle when use formula

${ \boxed{✜\underline{ \boxed{ \sf{\: Circumference \: of \: circle= \: 2\pi \: r}}}✜}}$

➢ r = radius (25inch.)
➢ value of π is 3.14

${ \rule{70mm}{2.9pt}}$

$\large\underline{ \boxed{ \sf{✰\: Let's\:solve }}}$

$\sf{➛ \: Circumference \: of \: circle = 2 \times 3.14 \times 25} \\ \sf{➛ \: Circumference \: of \: circle =2 \times 78.5} \\ \sf{➛ \: Circumference \: of \: circle =157inch}$

★ Hence circumference of circle=157inch

$\large\underline{ \boxed{ \sf{➪\:157inch. }}}$

${ \rule{70mm}{2.9pt}}$

Hope it helps !

4 0

2 years ago

Can someone answer this please? Thanks! :)

Wittaler [7]

The Correct Answer is : 4x - 4 * 2

Hope This Helps :)

If it does please give brainliest answer xD

7 0

3 years ago

Read 2 more answers