It is a similar triangle so the side length of the smaller triangle (x and x-2) are in the same ratio as the bigger triangle (2x+5 and 2x-1). As the ratio is the same, you can equate them and solve for x.
Cos -2x or -cos2x, it's the difference.
Hello,
f(x)=2x²+1
f(ax+b)=2(ax+b)²+1=2(a²x²+2abx+b²)+1=2a²x²+4abx+2b²+1
af(x)+b=a(2x²+1)+b=2ax²+a+b
And f(ax+b)≠af(x)+b not linear
To find the inverse of a function, switch the x and the y and then solve for the new y. Like this:

. Subtract 5 from both sides to get

and then multiply both sides by 3. 3(x - 5) = y. B is your choice.