(1/2)*ln(2*y+1)=C-ln(cos(x)) equation
The teacher will be very surprised to see your correct solution 😉
The solution
Detail solution
Given the equation
$$\frac{\log{\left(2 y + 1 \right)}}{2} = c - \log{\left(\cos{\left(x \right)} \right)}$$
$$\frac{\log{\left(2 y + 1 \right)}}{2} = c - \log{\left(\cos{\left(x \right)} \right)}$$
Let's divide both parts of the equation by the multiplier of log =1/2
$$\log{\left(2 y + 1 \right)} = 2 c - 2 \log{\left(\cos{\left(x \right)} \right)}$$
This equation is of the form:
log(v)=p
By definition log
v=e^p
then
c - log(cos(x))
---------------
1/2
2*y + 1 = e
simplify
$$2 y + 1 = \frac{e^{2 c}}{\cos^{2}{\left(x \right)}}$$
$$2 y = \frac{e^{2 c}}{\cos^{2}{\left(x \right)}} - 1$$
$$y = \frac{e^{2 c}}{2 \cos^{2}{\left(x \right)}} - \frac{1}{2}$$
Sum and product of roots
[src]
/ 2*c \ / 2*c \
| e | | e |
re|-------| I*im|-------|
| 2 | | 2 |
1 \cos (x)/ \cos (x)/
- - + ----------- + -------------
2 2 2
$$\frac{\operatorname{re}{\left(\frac{e^{2 c}}{\cos^{2}{\left(x \right)}}\right)}}{2} + \frac{i \operatorname{im}{\left(\frac{e^{2 c}}{\cos^{2}{\left(x \right)}}\right)}}{2} - \frac{1}{2}$$
/ 2*c \ / 2*c \
| e | | e |
re|-------| I*im|-------|
| 2 | | 2 |
1 \cos (x)/ \cos (x)/
- - + ----------- + -------------
2 2 2
$$\frac{\operatorname{re}{\left(\frac{e^{2 c}}{\cos^{2}{\left(x \right)}}\right)}}{2} + \frac{i \operatorname{im}{\left(\frac{e^{2 c}}{\cos^{2}{\left(x \right)}}\right)}}{2} - \frac{1}{2}$$
/ 2*c \ / 2*c \
| e | | e |
re|-------| I*im|-------|
| 2 | | 2 |
1 \cos (x)/ \cos (x)/
- - + ----------- + -------------
2 2 2
$$\frac{\operatorname{re}{\left(\frac{e^{2 c}}{\cos^{2}{\left(x \right)}}\right)}}{2} + \frac{i \operatorname{im}{\left(\frac{e^{2 c}}{\cos^{2}{\left(x \right)}}\right)}}{2} - \frac{1}{2}$$
/ 2*c \ / 2*c \
| e | | e |
re|-------| I*im|-------|
| 2 | | 2 |
1 \cos (x)/ \cos (x)/
- - + ----------- + -------------
2 2 2
$$\frac{\operatorname{re}{\left(\frac{e^{2 c}}{\cos^{2}{\left(x \right)}}\right)}}{2} + \frac{i \operatorname{im}{\left(\frac{e^{2 c}}{\cos^{2}{\left(x \right)}}\right)}}{2} - \frac{1}{2}$$
-1/2 + re(exp(2*c)/cos(x)^2)/2 + i*im(exp(2*c)/cos(x)^2)/2
/ 2*c \ / 2*c \
| e | | e |
re|-------| I*im|-------|
| 2 | | 2 |
1 \cos (x)/ \cos (x)/
y1 = - - + ----------- + -------------
2 2 2
$$y_{1} = \frac{\operatorname{re}{\left(\frac{e^{2 c}}{\cos^{2}{\left(x \right)}}\right)}}{2} + \frac{i \operatorname{im}{\left(\frac{e^{2 c}}{\cos^{2}{\left(x \right)}}\right)}}{2} - \frac{1}{2}$$
y1 = re(exp(2*c)/cos(x)^2)/2 + i*im(exp(2*c)/cos(x)^2)/2 - 1/2