Find the domain and range of the function that is the solution to the differential equation
$$\frac{dy}{dx} = e^{x+y}$$
and whose graph passes through the origin - HSC - SSCE Mathematics Extension 1 - Question 14 - 2024 - Paper 1
Question 14
Find the domain and range of the function that is the solution to the differential equation
$$\frac{dy}{dx} = e^{x+y}$$
and whose graph passes through the origin.
(... show full transcript
Worked Solution & Example Answer:Find the domain and range of the function that is the solution to the differential equation
$$\frac{dy}{dx} = e^{x+y}$$
and whose graph passes through the origin - HSC - SSCE Mathematics Extension 1 - Question 14 - 2024 - Paper 1
Step 1
Show that for \theta < \sin^{-1}(\frac{8}{9}), the distance D(t) is increasing for all t > 0.
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Answer
The distance from the origin is given by:
D(t)=∣r(t)∣=(gVcosθt)2+(gVsinθ−2gt2)2.
To show that D(t) is increasing, we compute the derivative:
D′(t)=dtd(x2+y2)=x2+y2x⋅dx/dt+y⋅dy/dt.
Consequently, we will show that (D'(t) > 0) for all ( t > 0) when (\theta < \sin^{-1}(\frac{8}{9})) holds true, leading to increasing distance.