## 698 Reputation

15 years, 73 days

## how to evalf this....

question is : with(combinat): sum(numbcomb(80, x)*numbcomb(100, 27-x), x = 1 .. 27)

of course the following is ok

tot := 0; for x to 27 do tot := tot+numbcomb(80, x)*numbcomb(100, 27-x) end do: tot

## Plot---AspectRatio-defaut ratio sometime...

Maple 14

question1:

plot(2/(3*x)+x, x = -5 .. 5)

Though this is ok ：plot(2/(3*x)+x, x = -5 .. 5, y = -5 .. 5)

but ... lazy to set range of y axis at the very start.

question2：

how to plot more graph on different invertals  one time.

for example the intarvals [-5,5],[-1,1],[0,1]

## Display formula related problem,...

Maple

(&sum;)a[ijk](t)(x^(j))^((k))+b^(j)(t)=0,i=1,..,n.

click enter,and the font will be automatical converted to Times New Roman

but with error information about my subscript (j,k)

## series-...

s1 := series(sin(x), x, 6)

c1 := series(cos(x), x, 6)

e := exp(1)

e1 := series(e^x, x, 6)

how to make s1+c1 =  e1's form,but x-(1/6)*x^3+(1/120)*x^5+O(x^6)+(1-(1/2)*x^2+(1/24)*x^4+O(x^6))

## code-make-2x4-to 2x^4...

Maple

I mean when typing polynomials, convert the 2x4 to 2x^4,,,

for 4 is in the right

and sometimes I'm a little lazy(?).

...

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