Quadratic function is the key content of ninth grade mathematics and even the senior high school entrance examination. There are many aspects about quadratic function, such as the increase and decrease and maximum of quadratic function, the symmetry axis of image, the folding and translation of image, quadratic function and practical problems.

The basic expression of quadratic function is y=ax? +bx+c(a≠0). The highest degree of a quadratic function must be quadratic, and the image of a quadratic function is a parabola whose symmetry axis is parallel or coincident with the Y axis.

The expression of quadratic function is y=ax? +bx+c (and a≠0), which is defined as quadratic polynomial (or monomial). If the value of y is equal to zero, a quadratic equation can be obtained. The solution of this equation is called the root of the equation or the zero of the function.

Quadratic function history

Around 480 BC, Babylonians and China had found the positive root of quadratic equation by collocation method, but did not put forward the general solution. Around 300 BC, Euclid proposed a more abstract geometric method to solve quadratic equations.

In the 7th century, Brahmagupta of India was the first person who knew how to use algebraic equations, which allowed positive and negative roots. In 1 1 century, Elazemi of Arabia independently developed a set of formulas for finding positive solutions of equations. Abraham Bachyat introduced the complete solution of the quadratic equation of one variable to Europe for the first time in his book Liber embadorum.