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y^2+2y-35=0 equation

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Numerical solution:

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The solution

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 2               
y  + 2*y - 35 = 0
$$\left(y^{2} + 2 y\right) - 35 = 0$$
Detail solution
This equation is of the form
a*y^2 + b*y + c = 0

A quadratic equation can be solved
using the discriminant.
The roots of the quadratic equation:
$$y_{1} = \frac{\sqrt{D} - b}{2 a}$$
$$y_{2} = \frac{- \sqrt{D} - b}{2 a}$$
where D = b^2 - 4*a*c - it is the discriminant.
Because
$$a = 1$$
$$b = 2$$
$$c = -35$$
, then
D = b^2 - 4 * a * c = 

(2)^2 - 4 * (1) * (-35) = 144

Because D > 0, then the equation has two roots.
y1 = (-b + sqrt(D)) / (2*a)

y2 = (-b - sqrt(D)) / (2*a)

or
$$y_{1} = 5$$
$$y_{2} = -7$$
Vieta's Theorem
it is reduced quadratic equation
$$p y + q + y^{2} = 0$$
where
$$p = \frac{b}{a}$$
$$p = 2$$
$$q = \frac{c}{a}$$
$$q = -35$$
Vieta Formulas
$$y_{1} + y_{2} = - p$$
$$y_{1} y_{2} = q$$
$$y_{1} + y_{2} = -2$$
$$y_{1} y_{2} = -35$$
The graph
Rapid solution [src]
y1 = -7
$$y_{1} = -7$$
y2 = 5
$$y_{2} = 5$$
y2 = 5
Sum and product of roots [src]
sum
-7 + 5
$$-7 + 5$$
=
-2
$$-2$$
product
-7*5
$$- 35$$
=
-35
$$-35$$
-35
Numerical answer [src]
y1 = 5.0
y2 = -7.0
y2 = -7.0