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Please tell me if you DON'T understand... :)

Letting a₁ be the first term, we have  that

[ a₁  + d(5-1)]   + [a₁ + d(10-1)]  = 11.5     simplify

2a₁ + 4d + 9d   =  11.5

2a₁ + 13d  = 11.5     →   2a₁  = 11.5 - 13d   (1)

And the sum of the first 20 terms can be expressed by :

85 = (20/2) [ 2a₁ + (20-1)d ]

85 = 10 [2a₁ + 19d]   (2)

Substituting (1)  into (2), we have

85 = 10 [ 11.5 - 13d + 19d]

85  = 115 + 60d

-30  = 60d     divide both sides by 60

-1/2  = d

And using (1)  to find the first term , a₁, we have

2a₁ = 11.5 - 13(-1/2)

2a₁  = 11.5 + 6.5

2a₁  = 18

a₁  = 9

1/4 = 1 ÷ 4.00 = 0.25

:)

Cannot type the equations.. So, Here :D

http://www.wolframalpha.com/input/?i=limit+as+n+goes+to+infinity+of+(1%2B(2%2Fn))%5En

I didn't know it was possible.. LOL

You have more than the Admin......LOL!!!!!

(1-1/t^2)/(1/t-t) = -1/t     get common denominators on top and bottom

(  [t^2 - 1] / t^2  )   / (  [ 1 - t^2] / t )   =       factor a -1 out of the numerator on the right

( - [ 1 - t^2] / t^2 )  / ( [ 1 - t^2] / t )  =

( - [ 1 - t^2] / t^2 )  * ( t / [ 1 - t^2] )   =

( - [ 1 - t^2] / [ 1 - t^2] ) * ( t / t^2 )  =

- t  / t^2   =

-1 / t

It sums up or adds a number of terms, generally large, together to get a final total or result. Example: Sum up all the following terms: 5, 10, 15, 20, 25.......all the way up to the thousanth term. And it will sum them all up. You can try it on this example. I get: 2,502,500. See if you can get the same answer.

You could just type "x,y,x" ex. :)

.57^6

=0.0342964472

:)

=  ( t^2 -1)/t^2   / (1-t^2)/t

= (t^2-1)/t^2   x   t/(1-t^2)  = (t^2 -1)/t  x   1/(1-t^2)     Multiply by  -1/-1

(1-t^2)/(-t)  x 1/(1-t^2) =   - 1/t

3^2 = 9

4^2 = 16     SO the sqrt12 is BETWEEN   3  and 4

Correct!

7x - 9 + 5x + 14 + 2(3x - 8) 

the first thing to do is to distribute the "2" through the parenthesis to both terms inside of it. Now you have: 

7x - 9 + 5x + 14 + 6x - 16 

Now, combine like terms: 

18x - 11

What is the percentage error of 9.7562130178 out of 10

1 - [9.7562130178 / 10] X 100 =2.437869822% "Percentage error"

What is the simplified form of 7x-9+5x+14+2(3x-8)

=18x - 11

Thanks, CPhill! and +5 for you!

Excellent, DS   .....5 pts  !!!

First, do the exponent.

1.07^3 = 1.225043

Then Multiply the answer by 50 to GET your final answer.

1.225043*50 = 61.25215

Your final answer is 61.25215

y=x+2   (1)

y=-x       (2)

We can directly substitute (2)  into (1)  for y   ...  and we have

-x  = x + 2      subtract x from both sides

-2x  = 2        divide both sides by -2

x = -1

And using (2)  ....y  = -x  ....... so y = -(-1)   = 1

If you can ask here what that is, you can answer that too. Sorry if you felt that this was rude.

9 x 7 = 63

63 is your answer!

We are just using the distributive property on these.

1.   √3 (5+√3)   = √3*5 + √3 *√3   =   5*√3  +  3

2.   2√5(√6+2)  = 2√5 * √6  + 2√5 * 2  =  2√30 + 4√5

3.   -3√3(2+√6)   -3√3 * 2 + -3√3 * √6   =   -6√6 + -3√18  = -6√6 + -3√(9*2)  = -6√6 + -3*3√2  =

-6√6 + -9√2

4.   √3(-5√10+√6)  =  -5*√30 + √3 *√6  =   -5√30 + √18   = -5√30 + √(9*2)  =  -5√30 + 3√2

Example     cos_1 (.8)

Push teh following buttons

.  8    2nd  acos  then the = button

Works fine.

THE WRONG ANSWER WAS PROVIDED BY ME! MY BAD!

Mmmmm....I just tried it......seems to work fine....!!!