PLEAASE HELP I HAVE LITERALLY NO TIME LEFT I WILL GIVE BRAINLY SOON PLS HELP
1 answer:
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Answer:
Rs 19.20
Step-by-step explanation:
Buying price = Rs 20
Profit = 20% = 0.20 × 20 = Rs 4
Selling price = buying price + profit = Rs 20 + Rs 4 = Rs 24
He wants to make a 25% profit.
Let's say he should buy the pen at Rs 'a' in order to make that amount of profit.
∴ a + = 24
1.25a = 24
a =
So he should buy the pen at Rs 19.20
Assume 
.
![\dfrac{\mathrm d}{\mathrm dx}[7x^2+xy+7y^2]=\dfrac{\mathrm d}{\mathrm dx}[15]](https://tex.z-dn.net/?f=%5Cdfrac%7B%5Cmathrm%20d%7D%7B%5Cmathrm%20dx%7D%5B7x%5E2%2Bxy%2B7y%5E2%5D%3D%5Cdfrac%7B%5Cmathrm%20d%7D%7B%5Cmathrm%20dx%7D%5B15%5D)
The slope of the tangent line to the curve at
is then 
, so the tangent to 
has slope
The point-slope form of the tangent line is then
The slope of the tangent line to the curve at
The point-slope form of the tangent line is then