PhysChemTutor's answer to Zwen's Secondary 4 A Maths Singapore question.

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PhysChemTutor
Physchemtutor's answer
1551 answers (A Helpful Person)
1st
Zwen
Zwen
3 years ago
Oh ok, thanks. But is there detailed steps to this qn? Because it is 4 marks, I don't think giving a short answer like this will help.
PhysChemTutor
PhysChemTutor
3 years ago
Is this the whole question. It will be nice if can see the whole question.
PhysChemTutor
PhysChemTutor
3 years ago
By the way, i did skip one or 2 steps.
J
J
3 years ago
Have you learnt integration by parts? If yes I can show you a solution employing its use
Zwen
Zwen
3 years ago
It just says find the following integral, that's all. No other useful info.
Zwen
Zwen
3 years ago
To J: Yes I've learnt that. Please show me, thanks for the help.
PhysChemTutor
PhysChemTutor
3 years ago
I doubt it can be done by using by-parts
PhysChemTutor
PhysChemTutor
3 years ago
I think the question may want you to initiate the derivative first then do the inverse differentiation concept.
Zwen
Zwen
3 years ago
To Yong: I dunno anything, this qn is so hard oh my gosh. I can't even figure out the first step.
J
J
3 years ago
Have you learnt integration by substitution? That would definitely be possible
J
J
3 years ago
let u = x²

Then du/dx = 2x

→"du = 2x dx "

∫ xeˣ² dx

= ∫ (½ eˣ²) 2x dx

= ∫ ½ eᵘ du

= ½ eᵘ

= ½eˣ² + c

(Change the u back to x²)
J
J
3 years ago
Alternatively, this is directly integrable so just write this :


∫ xeˣ² dx

= ½ ∫ 2xeˣ² dx

= ½ ∫ (d/dx (eˣ²) ) dx

= ½ eˣ² + c
J
J
3 years ago
To Yong : it can be done, but it is quite advanced.

https://math.stackexchange.com/questions/2217850/integration-by-parts-int-xex2-dx
Zwen
Zwen
3 years ago
Ughhhh, alright thank you yall, both Yong and J