In junior high school mathematics, solving a quadratic equation is a very important knowledge point. The root formula is one of the effective methods to solve the quadratic equation of one variable. The general form of unary quadratic equation is ax2+bx+c=0, where A, B and C are known coefficients. The expression of the root formula is x=(-b+v(b2-4ac))/2a. This formula means: first calculate the value of b2-4ac, and then find the root to get a real number. Add or subtract this real number from -b, and then divide it by 2a to get two roots of the equation.
It should be noted that if the value of b2-4ac is negative, then the real number solution cannot be obtained, and the solution of the equation is complicated. At this time, the expression of the root formula is x=(-b+v(4ac-b2)i)/2a, where i is an imaginary unit. In addition to finding the root formula, there are other methods to solve the linear equation in junior high school mathematics, such as collocation method and formula method. But finding the root formula is the most basic method and one of the most commonly used methods.
By studying the root formula, we can understand the essence and solution of quadratic equation in one variable more deeply. At the same time, we can also apply this method to a wider range of mathematical fields, such as physics, engineering and so on. Therefore, it is very important for junior high school mathematics learners to master the formula of finding roots. Only by mastering this formula skillfully in theory and practice can we solve various mathematical problems better.
Rooting method
Divide the integer part of the square root into two-digit segments from the unit to the left, separated by apostrophes, and divided into several segments, indicating how many digits the square root is. According to the number in the first paragraph on the left, calculate the number of square root high places, subtract the square of the number of high places from the number in the first paragraph, and write the number in the second paragraph to the right of their difference to form the first remainder.
Multiply the obtained high order by 20 to try to divide the first remainder, and the obtained large integer is used as the trial quotient. Multiply this quotient by 20 times the high order of the quotient, and then multiply it. If the product is less than or equal to the remainder, the quotient is the second bit of the square root. If the product is greater than the remainder, please reduce the trial quotient and try again. In the same way, continue to look for numbers on other digits of the square root.