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3 years ago

What is the first operation that you will perform when you evaluate this expression? 12 + (18 - 2) x 3 ÷ 24

Mathematics

1 answer:

Temka [501]3 years ago

7 0

Answer:

(18-2)

Step-by-step explanation:

Use the formula of PEMDAS to determine which is first.

The p stands for parentheses so you would perform that operation first.

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Write 124 in scientific notation.

Artemon [7]

Answer:

Step-by-step explanation:

Write 124 in scientific notation.

Then, in scientific notation, 124 is written as 1.24 × 102. Actually, converting between "regular" notation and scientific notation is even simpler than I just showed, because all you really need to do is count decimal places.

6 0

3 years ago

Read 2 more answers

Write down the explicit solution for each of the following: a) x’=t–sin(t); x(0)=1

Kay [80]

Answer:

a) x=(t^2)/2+cos(t), b) x=2+3e^(-2t), c) x=(1/2)sin(2t)

Step-by-step explanation:

Let's solve by separating variables:

$x'=\frac{dx}{dt}$

a) x’=t–sin(t), x(0)=1

$dx=(t-sint)dt$

Apply integral both sides:

$\int {} \, dx=\int {(t-sint)} \, dt\\\\x=\frac{t^2}{2}+cost +k$

where k is a constant due to integration. With x(0)=1, substitute:

$1=0+cos0+k\\\\1=1+k\\k=0$

Finally:

$x=\frac{t^2}{2} +cos(t)$

b) x’+2x=4; x(0)=5

$dx=(4-2x)dt\\\\\frac{dx}{4-2x}=dt \\\\\int {\frac{dx}{4-2x}}= \int {dt}\\$

Completing the integral:

$-\frac{1}{2} \int{\frac{(-2)dx}{4-2x}}= \int {dt}$

Solving the operator:

$-\frac{1}{2}ln(4-2x)=t+k$

Using algebra, it becomes explicit:

$x=2+ke^{-2t}$

With x(0)=5, substitute:

$5=2+ke^{-2(0)}=2+k(1)\\\\k=3$

Finally:

$x=2+3e^{-2t}$

c) x’’+4x=0; x(0)=0; x’(0)=1

Let $x=e^{mt}$ be the solution for the equation, then:

$x'=me^{mt}\\x''=m^{2}e^{mt}$

Substituting these equations in c)

$m^{2}e^{mt}+4(e^{mt})=0\\\\m^{2}+4=0\\\\m^{2}=-4\\\\m=2i$

This becomes the solution m=α±βi where α=0 and β=2

$x=e^{\alpha t}[Asin\beta t+Bcos\beta t]\\\\x=e^{0}[Asin((2)t)+Bcos((2)t)]\\\\x=Asin((2)t)+Bcos((2)t)$

Where A and B are constants. With x(0)=0; x’(0)=1:

$x=Asin(2t)+Bcos(2t)\\\\x'=2Acos(2t)-2Bsin(2t)\\\\0=Asin(2(0))+Bcos(2(0))\\\\0=0+B(1)\\\\B=0\\\\1=2Acos(2(0))\\\\1=2A\\\\A=\frac{1}{2}$

Finally:

$x=\frac{1}{2} sin(2t)$

7 0

3 years ago

A pole is centre of a circular pond of diameter 14m. Total height of a pole is 20m and its part inside a water is 3.5m. If a man

monitta

Answer:

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4 0

3 years ago

Name an altitude for ABC

valina [46]

Altitude is another word for height so it would be the first answer

8 0

3 years ago

Read 2 more answers

Graph the linear equation to -2x+7y=-21

mr Goodwill [35]

Answer:

This equation is in standard form, so to make graphing easier you need to put it in y=mx+b form or slope, intercept form.