[dongonaeatu]

find the area of the shades region; y=x^2-4

the first area is where x is 0 and x is 2

second area where x is 2 and x is 3

first area is underneath x axis, second area above x axis

so i did limits and got -16/3 for first area ( i know you just make this positive) but for the second area which is above the x axis i got -41/3? how can this be? someone help

[Sketch]

Can i ask what the answer to the question is?

[dongonaeatu]

(Original post by Sketch)
Can i ask what the answer to the question is?

well first area i got -16/3 but as its underneath x-axis you just count it as positive so 16/3. second area i got -41/3 but it is above x axis. I should add both numbers together but surely im wrong if the area above the x axis is a negative? so either 19 or -25/3 lol. what did you get can you help

[sputum]

If you run x=3 through your integral what do you get?

[dongonaeatu]

(Original post by sputum)
If you run x=3 through your integral what do you get?

-3

[sputum]

(Original post by dongonaeatu)
-3

Keerect!
Now take what you got for x=2 away from this.

[Sketch]

hmmm, for the second area i got 7/3.. are you sure your method is correct? talk me through your working out for the second area..

[dongonaeatu]

oh.. so is it meant to be -3--41/3? with 2 minus's making a plus

[dongonaeatu]

(Original post by Sketch)
hmmm, for the second area i got 7/3.. are you sure your method is correct? talk me through your working out for the second area..

second area i did

[(3)^3/3-4(3)] - [(2)^3/3-4(2)]= -41/3

wait i just did it again... i got 7/3 this time

wtf it will still end up being negative -3+7/3= -2/3

oh wait.. the whole second area is 7/3 so its 16/3+7/3= 23/3 for the whole area?

[sputum]

7/3 is good

[Sketch]

The area in this case would be the integral of the "above x axis" area, minus MINUS the integral of the "below x axis" area.. i.e. just take the sum of their absolute values..

[dongonaeatu]

the answer for the whole area is 23/3 yes or no

[Sketch]

where did the -3 come from may i ask?

[Sketch]

(Original post by dongonaeatu)
the answer for the whole area is 23/3 yes or no

yes!

[sputum]

(Original post by Sketch)
where did the -3 come from may i ask?

putting x=3 in y=x³/3 -4x

[dongonaeatu]

Thanks for the help you two i repped you both ;D

[dongonaeatu]

uh ran out of rep..sputnam i'll rep you later bro thanks