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3 years ago

In how many ways can you select two people from a group of 20 if the order of selection is not important?

Mathematics

1 answer:

Svetllana [295]3 years ago

3 0

That is 20C2 The number of combinations of 2 from 20

= 20 * 19 / 2*1 = 190 answer

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an electric can opener is worth 38 dollars when it is new. After each year it is worth half what it was the previous year. What

BigorU [14]

1 Year: 19
2 Years: 9.50
3 Years: 4.75
4 Years: 2.38 (2.375, but rounded)

7 0

3 years ago

Which value is NOT a solution of 8x3 – 1 = 0?

Tpy6a [65]

<u><em>Note: As you may have unintentionally missed to add the value choices. But, I would make sure to explain the concept so that you may improve your understanding in terms of solving these type of questions.</em></u>

Answer:

Any value other than the values $x=\frac{1}{2},\:x=-\frac{1}{4}+i\frac{\sqrt{3}}{4},\:x=-\frac{1}{4}-i\frac{\sqrt{3}}{4}$ will not be a solution of $8x^3\:-\:1\:=\:0$ .

Step-by-step explanation:

Considering the equation

$8x^3\:-\:1\:=\:0$

Steps to solve the equation

$8x^3-1=0$

$\mathrm{Add\:}1\mathrm{\:to\:both\:sides}$

$8x^3-1+1=0+1$

$\mathrm{Simplify}$

$x^3=\frac{1}{8}$

$\mathrm{Divide\:both\:sides\:by\:}8$

$\frac{8x^3}{8}=\frac{1}{8}$

$\mathrm{Simplify}$

$x^3=\frac{1}{8}$

$\mathrm{For\:}x^3=f\left(a\right)\mathrm{\:the\:solutions\:are\:}x=\sqrt[3]{f\left(a\right)},\:\sqrt[3]{f\left(a\right)}\frac{-1-\sqrt{3}i}{2},\:\sqrt[3]{f\left(a\right)}\frac{-1+\sqrt{3}i}{2}$

$x=\sqrt[3]{\frac{1}{8}},\:x=\sqrt[3]{\frac{1}{8}}\frac{-1+\sqrt{3}i}{2},\:x=\sqrt[3]{\frac{1}{8}}\frac{-1-\sqrt{3}i}{2}$

So,

$x=\frac{1}{2},\:x=-\frac{1}{4}+i\frac{\sqrt{3}}{4},\:x=-\frac{1}{4}-i\frac{\sqrt{3}}{4}$

Therefore,

Any value other than the values $x=\frac{1}{2},\:x=-\frac{1}{4}+i\frac{\sqrt{3}}{4},\:x=-\frac{1}{4}-i\frac{\sqrt{3}}{4}$ will not be a solution of $8x^3\:-\:1\:=\:0$ .

Keywords: solution, value

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7 0

3 years ago

2d+7/6-d-5/3=0 Tell me the answer

Inessa [10]

Answer:

d=1／2

Step-by-step explanation:

$2d + \frac{7}{6} - d - \frac{5}{3} = 0 \\ 2d - d = \frac{5}{3} - \frac{7}{6} \\ d = \frac{10}{6} - \frac{7}{6} \\ d = \frac{3}{6} \\ d = \frac{1}{2}$