ANSWER -
The quadratic formula is ax^2 + bx + c = 0, so we need to check if the given equations can be rewritten in this form.
x^4 – 6x^2 – 27 = 0 is quadratic in form, since it can be rewritten as (x^2)^2 - 6(x^2) - 27 = 0, where a = 1, b = -6, and c = -27.
3x^4 = 2x is not quadratic in form, since it can be simplified to 3x^3 = 2, which is not in the form ax^2 + bx + c = 0.
2(x + 5)^4 + 2x^2 + 5 = 0 is not quadratic in form, since it contains a fourth power term and the variables x and (x + 5) are not combined in a quadratic manner.
6(2x + 4)^2 = (2x + 4) + 2 can be simplified to 24x^2 + 44x - 10 = 0, which is quadratic in form, since it can be rewritten as 24x^2 + 44x - 10 = 0, where a = 24, b = 44, and c = -10.
6x^4 = -x^2 + 5 is not quadratic in form, since it contains a fourth power term and a linear term, which are not combined in a quadratic manner.
8x^4 + 2x^2 – 4x = 0 is quadratic in form, since it can be rewritten as 8(x^2)^2 + 2(x^2) - 4x = 0, where a = 8, b = 2, and c = 0.
Therefore, the quadratic equations in the given set are x^4 – 6x^2 – 27 = 0, 6(2x + 4)^2 = (2x + 4) + 2, and 8x^4 + 2x^2 – 4x = 0.