Question

Solve the quadratic. 4x^2+4-20=0 brainlist if you explain

Answer 1

Answer:

• x = -1/2(1 +√21) ≈ -2.79129
• x = -1/2(1 -√21) ≈ 1.79129

Step-by-step explanation:

We assume the middle term is supposed to be 4x.

We can remove a common factor of 4 to simplify this a bit.

  x^2 +x -5 = 0

This is of the form

  ax^2 +bx +c = 0

where a=1, b=1, c=-5.

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The quadratic formula gives the solutions as ...

  $x=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}$

Filling in the given coefficients, we have ...

  x = (-1 ±√(1^2 -4·1·(-5)))/(2·1)

  x = (-1±√21)/2

The solutions are x = -1/2(1 +√21) and -1/2(1 -√21).

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If what you wrote is what you intend, then the equation simplifies to 4x^2 -16 = 0.

Dividing by 4 and factoring the difference of squares gives ...

  x^2 -4 = 0

  (x -2)(x +2) = 0

These factors are zero (hence their product is 0) for the values x = 2 and x = -2.

The solutions are x=2 and x=-2.