Alan

I took the picture from the site I referenced.  You can ask it "Show me an explanation" after it has done the calculation, and this will include the graph.

.

If you are referring to the calculator on the home page here, then select the "create a graph" segment on the bottom right of the calculator.

. 

Another way of looking at it:

Probability of no heads                                       1/2³

Probability only the  first coin is a head                 1/2³

Probability only the 2nd coin is a head                  1/2³

Probability only the 3rd coin is a head                   1/2³

-----------------------------------------------------------

Overall probability of fewer than 2 heads              4*1/2³  =  4/8   =  1/2

.

log₉(log₉(x))=0  means log₉(x) = 9⁰, so log₉(x) = 1 

log₉(x) = 1 means x = 9¹, so x = 9

.

Assuming the distribution is Normal (Gaussian) then the percentage is 15.87%

Angles in a triangle must sum to 180° so

k + k+10 + k+20 = 180

or

3k + 30 = 180

3k = 150

k = 50

So the angles are 50°, 60° and 70°

.

You can do this on the calculator here using the "Equation" mode:

.

$${factor}{\left({\mathtt{1\,296}}{\mathtt{\,\times\,}}{\mathtt{60}}\right)} = {{\mathtt{2}}}^{{\mathtt{6}}}{\mathtt{\,\times\,}}{{\mathtt{3}}}^{{\mathtt{5}}}{\mathtt{\,\times\,}}{\mathtt{5}}$$

So C is the answer (noting that it should be interpreted as 2^6 x 3^5 x 5)

.

Do you want (-7)² = 49  or  -(7²) = -49 ?

.