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2 years ago

Find the middle number between three and 20

Mathematics

1 answer:

zlopas [31]2 years ago

4 0

In order to find it, add 20 and 3. That equals 23 and divide by two. It’ll equal 11.5

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Please i need an answer urgently. Sum of 3 terms are 252, first term is 192. Find common ratio

Viefleur [7K]

Answer:

$r=\frac{1}{4}\\\\r=-\frac{5}{4}$

Step-by-step explanation:

<u>Geometric Sequences</u>

The geometric sequence is given as:

$a_1, a_1r, a_1r^2, a_1r^3,..., a_1r^{n-1}$

Where n is the number of the term, n≥1, and r is the common ratio.

The sum of n terms of the geometric sequence is given by:

$\displaystyle S_n=a_1\frac{r^n-1}{r-1}$

We are given: S3=252, a1=192, thus substuting:

$\displaystyle 252=192\frac{r^3-1}{r-1}$

Dividing by 12:

$\displaystyle 21=16\frac{r^3-1}{r-1}$

Recall that:

$r^3-1=(r-1)(r^2+r+1)$

Substituting:

$\displaystyle 21=16\frac{(r-1)(r^2+r+1)}{r-1}$

Simplifying:

$21=16(r^2+r+1)=16r^2+16r+16$

Rearranging:

$16r^2+16r+16-21=0$

16r^2+16r-5=0

Rewriting:

$16r^2-4r+20r-5=0$

Factoring:

$4r(4r-1)+5(4r-1)=0$

$(4r-1)(4r+5)=0$

Solving:

$r=\frac{1}{4}\\\\r=-\frac{5}{4}$

Both solutions are valid

6 0

3 years ago

What is the lcm of 6 and 7

faust18 [17]

The lcm of 6 and 7 is 42.

3 0

3 years ago

Read 2 more answers

Suppose you add 10% of a number to the number, and then you subtract 10% of the total. Is the result greater than, less then, or

anyanavicka [17]

Let's say the number is 9. 10% of 9 is 0.9. Add that to 9 and you would get 9.9. 10% of 9.9 is 0.99. Subtract and you would get 8.91. Then you could do the rest.

5 0

3 years ago

Study quadrilateral ABCD. Which graph of ABCD shows the reflection of quadrilateral ABCD across the line y=x

algol13

Answer:

graph C

Step-by-step explanation:

3 0

3 years ago

If , find the value of 2 square root of 17-x = 2x-10, find the value of x/4.

ira [324]

$2 \sqrt{17-x} =2x-10\ \ \ \ \Rightarrow\ \ \ D:(17-x \geq 0\ \ \ and\ \ \ 2x-10 \geq 0)\\.\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x \leq 17\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x \geq 5\\\\.\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ D=\\\\2 \sqrt{17-x} =2(x-5)\ /:2\\\\ \sqrt{17-x} =x-5\ \ \ \Rightarrow\ \ \ (\sqrt{17-x})^2 =(x-5)^2\\\\17-x=x^2-10x+25\\\\$

$x^2-9x+18=0\\\\ x^2-3x-6x+18=0\\\\x(x-3)-6(x-3)=0\\\\(x-3)(x-6)=0\ \ \ \ \Leftrightarrow\ \ \ (x-3=0\ \ \ \ or\ \ \ \ x-6=0)\\\\x=3\ \notin\ D\ \ \ \ \ \ \ \ \ \ \ x=6\ \in\ D\ \ \ \Rightarrow\ \ \ \frac{x}{4} = \frac{6}{4} =1.5\\\\Ans.\ \frac{x}{4} =1.5$

7 0

3 years ago