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The roots of the quadratic function y = 1 / 2 x 2 − 3x + 5 / 2 are the places where the graph intersects the x-axis, the values x = 1 and x = 5. They can be found via the quadratic formula. In elementary algebra, the quadratic formula is a closed-form expression describing the solutions of a quadratic equation.
A quadratic function without real root: y = (x − 5) 2 + 9. The "3" is the imaginary part of the x-intercept. The real part is the x-coordinate of the vertex. Thus the roots are 5 ± 3i. The solutions of the quadratic equation + + = may be deduced from the graph of the quadratic function = + +, which is a parabola.
A root of degree 2 is called a square root and a root of degree 3, a cube root. Roots of higher degree are referred by using ordinal numbers, as in fourth root, twentieth root, etc. The computation of an n th root is a root extraction. For example, 3 is a square root of 9, since 3 2 = 9, and −3 is also a square root of 9, since (−3) 2 = 9.
Denoting the two roots by r 1 and r 2 we distinguish three cases. If the discriminant is zero the fraction converges to the single root of multiplicity two. If the discriminant is not zero, and |r 1 | ≠ |r 2 |, the continued fraction converges to the root of maximum modulus (i.e., to the root with the greater absolute value).
The square root of a univariate quadratic function gives rise to one of the four conic sections, almost always either to an ellipse or to a hyperbola. If a > 0 , {\displaystyle a>0,} then the equation y = ± a x 2 + b x + c {\displaystyle y=\pm {\sqrt {ax^{2}+bx+c}}} describes a hyperbola, as can be seen by squaring both sides.
The square root of any integer is a quadratic integer, as every integer can be written n = m 2 D, where D is a square-free integer, and its square root is a root of x 2 − m 2 D = 0. The fundamental theorem of arithmetic is not true in many rings of quadratic integers.
where C is a constant approximately equal to 0.625 735 8072. [23] In other words, the expected number of real roots of a random polynomial of high degree is lower than the natural logarithm of the degree.
It is a consequence of the first two equations that r 1 + r 2 is a square root of α and that r 3 + r 4 is the other square root of α. For the same reason, r 1 + r 3 is a square root of β, r 2 + r 4 is the other square root of β, r 1 + r 4 is a square root of γ, r 2 + r 3 is the other square root of γ. Therefore, the numbers r 1, r 2, r 3 ...