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# help with maths...am I just being really stupid?? Watch

1. Okay so I'm just working through the OCR Core 3 maths specimen paper, and to find the area under a curve I have to integrate (4x+1)^-1/2

Now I thought this would work out as 1/4 x 1/2(4x+1)^1/2 and therefore 1/8(4x+1)^1/2

But the answer scheme has it down as being 1/2(4x+1)^1/2

Is the answer scheme wrong or am I just being really thick? I am majorly hungover from a night out last night so the latter wouldn't surprise me tbh.

But I am aware that the specimen papers and answer schemes aren't as vigorously checked as real papers, so it is possible it's wrong.

Help is appreciated
2. Differentiate your answer and the mark scheme's answer, and you'll see the mistake you've made.
3. Ohh yh I know what i did...I multiplied by the new power rather than the inverse. Thanks
4. (Original post by alexKS)
Okay so I'm just working through the OCR Core 3 maths specimen paper, and to find the area under a curve I have to integrate (4x+1)^-1/2

Now I thought this would work out as 1/4 x 1/2(4x+1)^1/2 and therefore 1/8(4x+1)^1/2

But the answer scheme has it down as being 1/2(4x+1)^1/2

Is the answer scheme wrong or am I just being really thick? I am majorly hungover from a night out last night so the latter wouldn't surprise me tbh.

But I am aware that the specimen papers and answer schemes aren't as vigorously checked as real papers, so it is possible it's wrong.

Help is appreciated
If y=(4x+1)^1/2
so dy/dx=(1/2)*4*(4x+1)^(-1/2)=2(4x+1)^-1/2
So the integral of (4x+1)^-1/2 must be 1/2(4x+1)^1/2

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