Photo AI

The point P lies on the curve with equation y = 4e^{2x-1} - Edexcel - A-Level Maths Pure - Question 2 - 2008 - Paper 5

Question icon

Question 2

The-point-P-lies-on-the-curve-with-equation--y-=-4e^{2x-1}-Edexcel-A-Level Maths Pure-Question 2-2008-Paper 5.png

The point P lies on the curve with equation y = 4e^{2x-1}. The y-coordinate of P is 8. (a) Find, in terms of ln 2, the x-coordinate of P. (b) Find the equation o... show full transcript

Worked Solution & Example Answer:The point P lies on the curve with equation y = 4e^{2x-1} - Edexcel - A-Level Maths Pure - Question 2 - 2008 - Paper 5

Step 1

Find, in terms of ln 2, the x-coordinate of P.

96%

114 rated

Answer

To find the x-coordinate of point P, we start by substituting the known y-coordinate into the curve equation:

8=4e2x18 = 4e^{2x-1}

Now, we simplify:

e2x1=2e^{2x-1} = 2

Taking the natural logarithm of both sides gives:

2x1=extln(2)2x - 1 = ext{ln}(2)

Solving for xx results in:

2x=extln(2)+12x = ext{ln}(2) + 1 x = rac{1}{2}( ext{ln}(2) + 1)

Step 2

Find the equation of the tangent to the curve at the point P in the form y = ax + b, where a and b are exact constants to be found.

99%

104 rated

Answer

To find the equation of the tangent line, we need the derivative of the curve. First, we differentiate the curve equation:

y=4e2x1y = 4e^{2x-1}

Using the chain rule:

dydx=4imese2x1imes2=8e2x1\frac{dy}{dx} = 4 imes e^{2x-1} imes 2 = 8e^{2x-1}

Next, we evaluate this derivative at the point where x=12(extln(2)+1)x = \frac{1}{2}( ext{ln}(2) + 1):

Since we know that:

e2x1=2e^{2x-1} = 2

Then:

dydx=8×2=16\frac{dy}{dx} = 8 \times 2 = 16

Thus, the slope of the tangent at point P is 16.

Now we can use the point-slope formula for the tangent line, which passes through point P(\frac{1}{2}( ext{ln}(2) + 1), 8):

y8=16(x12(extln(2)+1))y - 8 = 16(x - \frac{1}{2}( ext{ln}(2) + 1))

Expanding this equation gives:

y=16x8+8+8extln(2)=16x8+8extln(2)y = 16x - 8 + 8 + 8 ext{ln}(2) = 16x - 8 + 8 ext{ln}(2)

Thus, we can write the tangent line in the form y=ax+by = ax + b:

a=16a = 16 and b=8+8extln(2)b = -8 + 8 ext{ln}(2).

Join the A-Level students using SimpleStudy...

97% of Students

Report Improved Results

98% of Students

Recommend to friends

100,000+

Students Supported

1 Million+

Questions answered

;