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Help needed please

I am so close to crying right now T.T spent 20 mins trying to figure this out. Someone please help me. E3D9BE24-10AC-4DDC-A82E-C0C4A56E7E76.jpg.jpeg

Reply 1

vc94

Did you try the product rule for (i) ?

Derivative of lnf(x) is f ' (x) / f(x)

Reply 2

Phoooo

I am having trouble with (iii)

(edited 5 years ago)

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Reply 3

vc94

Part (iii) becomes integral of 3(x^4)ln5x.

From part (i) the integral of -2(x^4)ln5x equals 0.4(x^5) [0.2 - ln5x] +c

So can you recogise what to do?

Reply 4

Phoooo

So I did this... but I don’t fully understand it EE5F711C-F5BD-49DB-A0B9-7B67B95921CF.jpg.jpeg

Reply 5

Nabz99

Thats what I get. Had tto use integration by parts adyer simplifying

Reply 6

Nabz99

I assumed that they use the word hence in part 3 because you must use the answer from part 2

Reply 7

vc94

Original post by vc94

Part (iii) becomes integral of 3(x^4)ln5x.

From part (i) the integral of -2(x^4)ln5x equals 0.4(x^5) [0.2 - ln5x] +c

So can you recogise what to do?

integral of 3(x^4)ln5x = integral of 3/-2*[-2(x^4)ln5x] = 3/-2*[0.4(x^5) [0.2 - ln5x]] +c = -0.6(x^5)[0.2 - ln5x] +c