Melody

Log_3(81^-.2)

=-0.2log_3(81)

=-0.2log_3(3^4)

=-0.2×4log_3(3)

=-0.8×1

=-0.8

=-4/5

Wed 21/10/15

1) Since back the the future has, at one point, today been the present.     (Wed 21/10 2015)

    I feel I must include this question.  It is at present one of the many that has NOT been answered. :)

    http://web2.0calc.com/questions/this-question-is-for-back-to-the-future-day

2) Inscribed circle - finding lengths.          Thanks Melody and Chris

    This is a repeat question.  Chris drew a great diagram and he did it a little differently from me.  

     http://web2.0calc.com/questions/geomerty-sum#r1

3) Partial Fractions       Melody

   http://web2.0calc.com/questions/partial-fraction-decomposition_1

4) Limit question   Thanks CPhill

  http://web2.0calc.com/questions/limit-question#r2

THAT IS AN EXCELLENT DIAGRAM CHRIS!   I am very impressed !

I was being a bit lazy but it is always better when a good pic is added.

consider the quadratic function x^2-(k+2)x+4=0

for what value of k does the quadratic function have real roots?

The roots will be reall when the determinant is greater than or equal to 0.

\(\triangle\ge0\\ (k+2)^2-4*1*4\ge0\\ k^2+4k+4-16\ge0\\ k^2+4k-12\ge0\\ (k+6)(k-2)\ge0\\ NOW\;\;consider\\ y=k^2+4k-12\\ \mbox{Since the coefficient of k is positive, this is a concave up parabola}\\ \mbox{So the expression will be greater than zero at the ends.} \mbox{The roots are -6 and 2}\\ \mbox{so the roots will be real when } \;\;k\le-6 \quad and \quad when \quad k\ge 2 \)

@@ What is Happening?  [Wrap4]    Tues  20/10/15     Sydney, Australia Time 6:25pm   ♪ ♫

Hi,

Here are the interest posts:

1)  Find the last digit of       3^ (a large number)     Thanks Heureka   

http://web2.0calc.com/questions/help_77727#r3

2) Tricky money one - For the juniors.           Melody

http://web2.0calc.com/questions/finding-the-constant#r2

3) How many lockers are open?  Great puzzle question.    Thanks CPhill

http://web2.0calc.com/questions/math-help_79172#r2

4) Inscribed circle - finding lengths.          Melody

http://web2.0calc.com/questions/geomerty-sum#r1

5)  Manipulating indices.     Melody and guest

http://web2.0calc.com/questions/neml-old-version#r2

6) James Bond, speed, distance and trigonometry.  

http://web2.0calc.com/questions/a-trigonometric-spy-story#r2

7) Find the min and max value of a function.

http://web2.0calc.com/questions/find-minimum-and-maximum-values#r1

If you want to comment an any issues please do so.    

Have a great day and I will see you next time    

Melody    ♪ ♫

What is -14.08333333333333.... in a mixed number?!?

= -14-0.08-0.0033333333

=-14-8/100 - 0.333333/100

=-14 -8/100 - 1/3 divided by 100

=-14 - 8/100  - 1/300

=-14 - 24/300  -1/300

= -14 - 25/300

= -14 - 1/12

\(=-14\frac{1}{12}\)

Heureka could you do it please ? 

This is what I think ://

lim_(x->0)(sinx/x)^cotx

=lim_(x->0)(1)^cotx

=1

1024^(4/5)

\(1024^{4/5}\\ =(2^{10})^{4/5}\\ =2^8\\ =256\)

(1024^4) /5 is not a radical either.  :/

3.8%+0.824[12.0%-3.8%]

0.038+0.824*(0.082)

0.105568

how does 19-(-5) equal 24? Why do I keep getting 14?

Think of negative numbers as cold numbers and positive numbers as hot numbers.

If you take cold air out of a room the room gets hotter.  So   - - = +        and 19 - -5 = 19+5 = 24

Maybe you get 24 when you do it on your calc because the calc does not understand   - - 

Although I just did it on my old Casio and it worked fine.   

I also just did it no the web2.0calc and it worked fine there too :)