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3 years ago

A=9,b= 12, c= 15 A+b=c

Mathematics

1 answer:

galina1969 [7]3 years ago

8 0

Answer:

Step-by-step explanation:

9+ 12=21

21– 15=6

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How many commuters must be randomly selected to estimate the mean driving time of Chicago commuters? We want 95% confidence that

lukranit [14]

Answer: 25 computers will be selected

Step-by-step explanation:

Where: Z -value at 95% confidence = 1.96; SD = Standard deviation = 10 minutes; N = Sample size; Margin error = 4 minutesSubstituting;4 = 1.96*10/Sqrt (N)Sqrt (N) = (1.96*10)/4 = 4.9N = 4.9^2 = 24.01 ≈ 25

5 0

3 years ago

What are the solutions of x^2-2x+5=0

sweet [91]

The solution of $x^{2}-2 x+5=0$ are 1 + 2i and 1 – 2i

Solution:

Given, equation is $x^{2}-2 x+5=0$

We have to find the roots of the given quadratic equation

Now, let us use the quadratic formula

$x=\frac{-b \pm \sqrt{b^{2}-4 a c}}{2 a}$ --- (1)

Let us determine the nature of roots:

Here in $x^{2}-2 x+5=0$ a = 1 ; b = -2 ; c = 5

$b^2 - 4ac = 2^2 - 4(1)(5) = 4 - 20 = -16$

Since $b^2 - 4ac < 0$ , the roots obtained will be complex conjugates.

Now plug in values in eqn 1, we get,

$x=\frac{-(-2) \pm \sqrt{(-2)^{2}-4 \times 1 \times 5}}{2 \times 1}$

On solving we get,

$x=\frac{2 \pm \sqrt{4-20}}{2}$

$x=\frac{2 \pm \sqrt{-16}}{2}$

$x=\frac{2 \pm \sqrt{16} \times \sqrt{-1}}{2}$

we know that square root of -1 is "i" which is a complex number

$\begin{array}{l}{\mathrm{x}=\frac{2 \pm 4 i}{2}} \\\\ {\mathrm{x}=1 \pm 2 i}\end{array}$

Hence, the roots of the given quadratic equation are 1 + 2i and 1 – 2i

6 0

3 years ago

On a map,the scale shown is 1inch:5miles.If an island is 75 square inches on the map,what is the actual area of the island?

Andreyy89

1 inch = 5 miles

1 square inch =25 square miles

25 square miles x 75 square inches = 1,875 square miles

Answer : 1,875 square miles

5 0

3 years ago

What is the solution to the system of equations ? Y=2/3 x + 3 X= - 2

Firdavs [7]

Answer:

x = -2, y = 5/3

Step-by-step explanation:

we have the value of x already (-2).

x=-2

Plug it into the first equation y = 2/3x+3

y = 2/3(-2)+3

y = -4/3+3

y = -4/3+9/3

y = 5/3

x = -2, y = 5/3

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3 years ago

The sum of two-thirds of a number and twenty

Ede4ka [16]

Answer:

2/3n + 20

Step-by-step explanation:

4 0

3 years ago