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Your "Triangle Quiz" is FALSE!!!!

Math is a term used from early times such as when the romans and greeks used to tell time and how money works math is used to show ways of doing a problem 

The same thing that it is WITH a calculator......!!!!!!!

W = Area/Length  = 4225 / 5      I'll let you take it from there  !!!!!

the answer is 4

consider the line L : kx+3y+12=0 , where k is a constant

i)find k if L is parallel to 6x-y-7=0

ii)find k if L is perpendicular to 6x-y-7=0

Putting the first line in slope-intercept form ,we have

y = (-k/3)x - 4

The second line, in the same form, is :

y = 6x - 7

Since parallel line have the same slope

-k/3   = 6      so k = -18

And perpendicular lines have negative reciprocal slopes, so

3/k   = 6       and k = 1/2

21. A and B can do a piece of work in 15 days; B and C can do it in 12 days while C and A can  finish it 20 days. In how many days will A,B,C finish it working together?

Let A, B, C be their work rates.....and we have.....

15A + 15B = 1   →      60A + 60B = 4    (1)

12B + 12C = 1   →     60B + 60C = 5     (2)

20A + 20C = 1   →     60A  + 60C  = 3    (3)

Subtract equation 3 from equation 1

60B - 60C = 1      add this to equation 2

120B = 6      B = 20 days to do the job

So B does 1/20 of the job in 1 day.....and using equation 1, we have

15A  + 15/20 = 1

15A  = 1/4    A can do 1/60 of the job in one day

And using equation 3, we have

20/60 + 20C = 1

20C  = 2/3

C = 30   so C does 1/30 of the job in one day

So, working together, we have

[1/20 + 1.60 + 1/30]x = 1

[3 + 1 + 2]/ 60  * x = 1

6/60 * x   = 1

1/10 (x)  = 1       x = 10 days  working together

Thanks Andre :)

P = −4 + 2.5n − 0.2n^2

Profit greatest when dP/dn=0

dP/dn = 2.5-0.4n

2.5-0.4n=0

2.5=0.4n

2.5/0.4=n

n=6.25 thousand widgets

n=6 thousand widgets to the nearest 1000.

Here is the graph to back up my answer.  

https://www.desmos.com/calculator/ula6msgsc8

Here's some of them :

1.  711

2. 349 x 10⁶ =   349,000,000

3. sqrt(5929) = 77

4. sqrt(0.8)  =  0.8944271909999159

5. 6.7  = 670%

9. sqrt (11025) = 105

10. cube root (3325) = 15

15.     521 / 1 .08 = P    where P is the original price he paid = about 482.41R

        So.....1.09 x P = about 525.82 R 

16.  (a) 12.23 /  21.43  

       (b) (42x-1 + 10)÷8 = 4     multiply both sides by 8

             42x - 1 + 10   = 32     simplify

             42x + 9   = 32            subtract 9 from both sides

             42x  = 23                   divide both sides by 42

                 x =  23/42

20. solve 9x− 7 (4x+ 2) = 3x+ 4 (4x+ 7)    simplify on both sides

               9x - 28x - 14  =  3x + 16x + 28  combine like terms

                -19x - `14 =   19x + 28        add 14 to both sides, subtract 19x from both sides

                 -38x = 42    divide both sides by -37

                     x = -42/38  =  -21/19

f(x)=3x^2-2

Yes it is a function... What about it ?

There is a calc on the home page.   

I know your fingers aren't broken because you can type ://

If this is

 \(\lim_{x\rightarrow 0}\frac{\frac{1}{x+4}-\frac{1}{4}}{x}\)

then write it as 

\(\lim_{x\rightarrow 0}\frac{\frac{1}{4(1+x/4)}-\frac{1}{4}}{x}\rightarrow \lim_{x\rightarrow 0}\frac{(1+x/4)^{-1}-1}{4x}\rightarrow \lim_{x\rightarrow 0}\frac{1-x/4+...-1}{4x}\rightarrow \lim_{x\rightarrow 0}\frac{-x/4+...}{4x}\rightarrow -\frac{1}{16}\)

I always think it's a good idea to draw a graph where possible:

.

You don't provide cost information but the relationship between W and L is given below:

A sample of copper with a mass of 63.5 g contains 6.02*10^23 atoms. Calculate the mass of a single copper atom.

(63.5)/(6.02*10^23)

=10.5481276*10^-23

=1.0548 * 10^-22 grams per atom

For a number to be divisable by 4 the last 2 digits must be divisable by 4.

HENCE one of these can never be divisable by 4

And if a number is not divisable by 4 it is impossible for it to be divisable by 8.

Why don't you try to work out the answer?

You can cheat a little and use a calculator if you need to :))

What is the square root of 2004 without a calculator?

I can see straight off without any working that it is just a little less then 45

Squaring numbers that end in 5 is really easy.

eg  75^2:     7*7+7=56 so the answer is 5625   works every time :))

So in your case 

4^2+4=20

so 45^2=2025

44^2=(40+4)^2=1600+2*40*4+16=1936

So it is between 44 and 45, closer to 45     

Since sqrt(2004) is an irrational number so it cannot be written exactly in digits no matter how many digits that you use. :)  

Hallo guest

use conversion factors of Mol=6.022 *10^23 atoms and 1 Mol (cu) = 63.546g (cu)

solve for LD: w = 0.002(2000-LD)

Having some trouble with this one, the LD equation I'm getting has some interesting signs (I get LD = -2000-500w) which I don't think makes intuitive sense.

\(\begin{array}{rcll} w &=& 0.002\cdot (2000-LD) \qquad &|\qquad :0.002\\\\ \dfrac{w}{0.002} &=& 2000-LD \qquad &|\qquad +LD\\\\ LD + \dfrac{w}{0.002} &=& 2000 \qquad &|\qquad - \dfrac{w}{0.002}\\\\ LD &=& 2000 - \dfrac{w}{0.002}\\\\ LD &=& 2000 - \dfrac{1}{0.002}\cdot w\\\\ LD &=& 2000 - \dfrac{1}{\frac{2}{1000}}\cdot w\\\\ LD &=& 2000 - \dfrac{1000}{2}\cdot w\\\\ \mathbf{LD} &\mathbf{=}& \mathbf{2000 - 500\cdot w} \end{array}\)

x2-3x+2=0

I think the intended question was 

\(x^2-3x+2=0\\ (x-2)(x-1)=0\\ x=2\;\;or\;\;x=1\)

(2x to the power of 1/3)(-4x to the power of 5/3) 

\(2x^{1/3}*-4x^{5/3}=-8x^{(5+1)/3} = -8x^2\)

Thanks Rom, you are probably right but

I thought that in chemistry it was taught that if a zeros were put after the point it implied that all the digits up to that one were significant.  Hence 5

If it had been written as 3100* 10^2   I would have said with confidence that there were only 2 significant figures.  ://

The 3 and the 1 are the significant digits here so just 2.