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If f(x)=x squared-2x and g(x) = 6x+4 for which is a value of x does (f+g)(x) =0

Sagot :

Answer:

For [tex]x = -2[/tex]

Step-by-step explanation:

Solving a quadratic equation:

Given a second order polynomial expressed by the following equation:

[tex]ax^{2} + bx + c, a\neq0[/tex].

This polynomial has roots [tex]x_{1}, x_{2}[/tex] such that [tex]ax^{2} + bx + c = a(x - x_{1})*(x - x_{2})[/tex], given by the following formulas:

[tex]x_{1} = \frac{-b + \sqrt{\Delta}}{2*a}[/tex]

[tex]x_{2} = \frac{-b - \sqrt{\Delta}}{2*a}[/tex]

[tex]\Delta = b^{2} - 4ac[/tex]

In this question:

[tex]f(x) = x^2 - 2x[/tex]

[tex]g(x) = 6x + 4[/tex]

[tex]f(x) + g(x) = (f+g)(x)  = x^2 - 2x + 6x + 4 = x^2 + 4x + 4[/tex]

Which is a value of x does (f+g)(x) =0

[tex]x^2 + 4x + 4[/tex]

Quadratic equation with [tex]a = 1, b = 4, c = 4[/tex]

So

[tex]\Delta = 4^{2} - 4*1*4 = 0[/tex]

[tex]x_{1} = \frac{-4 + \sqrt{0}}{2} = -2[/tex]

[tex]x_{2} = \frac{-4 - \sqrt{0}}{2} = -2[/tex]

For [tex]x = -2[/tex]