On the equation of line and circle in high school mathematics 1. Why can two linear equations be established simultaneously to obtain the linear system equation of the intersection of two lines? It is the derivation of the formula ax + by + C + n (AX + by + C) = 0. 2. There are three methods to find the chord length of a circle, one of which is obtained by using the root and coefficient of the quadratic equation of one variable. A linear equation and a circular equation are established simultaneously, and after elimination, we can get X1 + X2, X1 * x2 or Y1 + Y2, The relation of Y1 * Y2, and then the absolute value of chord length = what under the root sign (can't be typed out). How do you get this?

On the equation of line and circle in high school mathematics 1. Why can two linear equations be established simultaneously to obtain the linear system equation of the intersection of two lines? It is the derivation of the formula ax + by + C + n (AX + by + C) = 0. 2. There are three methods to find the chord length of a circle, one of which is obtained by using the root and coefficient of the quadratic equation of one variable. A linear equation and a circular equation are established simultaneously, and after elimination, we can get X1 + X2, X1 * x2 or Y1 + Y2, The relation of Y1 * Y2, and then the absolute value of chord length = what under the root sign (can't be typed out). How do you get this?

1. Let two linear equations be ax + by + C = 0, ax + by + C = 0, and let their intersection be (x0, Y0), then ax0 + by0 + C = 0ax0 + by0 + C = 0, so ax0 + by0 + C + n (ax0 + by0 + C) = 0. Obviously, ax + by + C + n (AX + by + C) = 0 is a passing point (x0, Y0), and each value of N represents a straight line, so it