# Integration question (1 Viewer)

#### highkeydropout

##### Member
Hi, does anyone know how to solve:

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#### qUiCkMaThS

##### New Member
Is the answer 21?

#### highkeydropout

##### Member
Is the answer 21?
i got 21 aswell, but I thought we subtract the bottom two from the area of the top? not sure tho

#### qUiCkMaThS

##### New Member
well, idk what I've done wrong, but if you find it, just point it out:

A1 + A2 + A3 = ATotal
A2 + A3 = 5A1/ 2

Since A1 = 3 x 2 = 6

ATotal = 15+6 = 21

i got 21 aswell, but I thought we subtract the bottom two from the area of the top? not sure tho
I've forgotten whether 'evaluate' changes what the question is asking....sorry about that!

• highkeydropout

#### highkeydropout

##### Member
well, idk what I've done wrong, but if you find it, just point it out:

A1 + A2 + A3 = ATotal
A2 + A3 = 5A1/ 2

Since A1 = 3 x 2 = 6

ATotal = 15+6 = 21

I've forgotten whether 'evaluate' changes what the question is asking....sorry about that!
no problem!! that's exactly what I got, it may be an error in the question, thank you!!

#### B1andB2

##### pyjama
no the answer seems right

-15?

Last edited:
• highkeydropout

#### B1andB2

##### pyjama
A1=6
A2= 3
A3 = 5(3x2)-2(3)/2 = 12

when you evaluate the integral (not the same as finding area) you consider the fact that below= negative

so solving the integral = -6+3-12 = -15

• Drdusk

#### highkeydropout

##### Member
A1=6
A2= 3
A3 = 5(3x2)-2(3)/2 = 12

when you evaluate the integral (not the same as finding area) you consider the fact that below= negative

so solving the integral = -6+3-12 =15
yesss that makes sense, thank you tooo!!

#### B1andB2

##### pyjama
are you sure it's 15?

it seems to be -15 the way im doing it

#### highkeydropout

##### Member
are you sure it's 15?

it seems to be -15 the way im doing it
my mistake it is -ve, sorry!

• B1andB2

#### notme123

##### Member
are you sure it's 15?

it seems to be -15 the way im doing it
I think it's -21. A1 should be -6 I think, not +6.

#### B1andB2

##### pyjama
I think it's -21. A1 should be -6 I think, not +6.
A1 means the area so it should be positive when you use it to find area 3

when you solve the integral though, you take the negative because it’s below

• highkeydropout

#### notme123

##### Member
A1 means the area so it should be positive when you use it to find area 3

when you solve the integral though, you take the negative because it’s below
Oh ok with the equation they give you they mean areas so it's positive. Understood

• highkeydropout and B1andB2

#### YonOra

##### Well-Known Member
A1=6
A2= 3
A3 = 5(3x2)-2(3)/2 = 12

when you evaluate the integral (not the same as finding area) you consider the fact that below= negative

so solving the integral = -6+3-12 = -15
How'd u get A2 to be 3. Having an elderly moment

• highkeydropout

#### B1andB2

##### pyjama
How'd u get A2 to be 3. Having an elderly moment
area of a triangle is half breadth times height

• highkeydropout

#### notme123

##### Member
• B1andB2

#### YonOra

##### Well-Known Member
No i was about to delete it. I thought A3 was A2 and i was like what

• notme123 and B1andB2

#### YonOra

##### Well-Known Member
Year 7 maths coming to bite me

• B1andB2