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Mathematics 10 Online
OpenStudy (anonymous):

H(t)=4-t^2/2-t .. find the domain and sketch the graph .. how to do this?

OpenStudy (anonymous):

\[H(t)=4-t^2/2-t\]

hartnn (hartnn):

very similar to your last question, where u stuck ?

OpenStudy (anonymous):

i ogt stuck again :/

hartnn (hartnn):

did u try to complete the square ?

OpenStudy (anonymous):

what do you think the domain should be? any critical thought?

OpenStudy (anonymous):

x should not be 2 ??

OpenStudy (anonymous):

i tried but it didnt work

hartnn (hartnn):

oh, is the question: \(\huge \frac{4-t^2}{2-t}\) ?

OpenStudy (anonymous):

yes

hartnn (hartnn):

then factor 4-t^2 can u ?

OpenStudy (anonymous):

You are right...x should not be 2...then?

hartnn (hartnn):

\(\huge use\quad a^2-b^2 = (a+b)(a-b)\)

OpenStudy (anonymous):

(2+t) (2-t)

hartnn (hartnn):

so now u can cancel 2-t from numerator and denominator, isn't it ?

OpenStudy (anonymous):

yup

hartnn (hartnn):

so your function is ?

OpenStudy (anonymous):

so H(t)= (2+t)

OpenStudy (anonymous):

\[(-\infty,0] U (2,+\infty)\]

OpenStudy (anonymous):

is the domain correct ?

hartnn (hartnn):

yes, thats the simplification of H(t) and its the straight line , which u can plot, right ? the domain is the values that x can take. x cannot be =2 as denom = 0 so it will be excluded from domain. why 0 to 2 cannot be in domain ?

hartnn (hartnn):

domain \((-\infty,2) U (2,+\infty)\)

OpenStudy (anonymous):

oh i see.. got it.. what about the graph?

hartnn (hartnn):

the graph will be same as that of line y= 2+x can u plot that ?

OpenStudy (anonymous):

i am getting (0,2) and (-2,0) .. is this correct??

hartnn (hartnn):

those intercepts are absolutely correct!

OpenStudy (anonymous):

You just normally draw a y=2+x graph w/o x=2 point

hartnn (hartnn):

now just draw a line joining them

OpenStudy (anonymous):

|dw:1350124772498:dw|

OpenStudy (anonymous):

is it correct ?

OpenStudy (anonymous):

No.

OpenStudy (anonymous):

The slope of the line on your graph is -1.

OpenStudy (anonymous):

Consider when x=0 and y=0

hartnn (hartnn):

u plotted -2,0 and 0,-2 instead

hartnn (hartnn):

plot (0,2) and (-2,0)

OpenStudy (anonymous):

|dw:1350125194635:dw|

hartnn (hartnn):

where is 0,2 ??

OpenStudy (anonymous):

When x=0, y=0+2 so (0,2) a point When y=0, x+2=0, x=-2, so (-2,0) a point

hartnn (hartnn):

0,2 means x-co-ordinate is 0 --->point on y-axis +2 ---->2 units UP

OpenStudy (anonymous):

|dw:1350125470946:dw|

OpenStudy (anonymous):

is this one correct ??

hartnn (hartnn):

now that is correct!

hartnn (hartnn):

now just exclude the point x=2 from your graph, because it does not belong to domain of the function

OpenStudy (anonymous):

how do i do that ?

hartnn (hartnn):

|dw:1350125753545:dw| just mark a small open circle when x=2

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