Daniel B. answered 03/29/21
A retired computer professional to teach math, physics
I interpret your equation as
x² + y² = (2x² + 2y² + 7x)²
The tangent will be of the form
y = px + q, where
p = dy/dx (also denoted y') and
q will be the result of constraining the line to go though the point (0, 1).
To find dy/dx by implicit differentiation, we differentiate the equation by dx,
while treating y as a function of x:
2x + 2yy' = 2(2x² + 2y² + 7x)(4x + 4yy' + 7)
At the point x = 0, y = 1:
2y' = 2(2)(4y' + 7)
2y' = 16y' + 28
y' = -2
So the tangent is of the form
y = -2x + q
At the point x = 0, y = 1:
1 = q
So the tangent is
y = -2x + 1