direct substitution的意思|示意

Direct substitution, also known as substitution of variables, is a mathematical principle which states that any expression can be simplified if one of its variables can be replaced by one or more known constants. This principle can be applied in geometry, algebra and trigonometry when solving equations and finding unknowns.

To illustrate the principle of direct substitution, consider the equation 5x + 3 = 12. To solve for the value of x, apply the direct substitution principle: replace “x” with “3”. Thus, the equation becomes 5x + 3 = 12 → 53 + 3 = 12 → 15 = 15. This equation is now solved, and we know that the value of x is 3.

Direct substitution can also be used in geometry to solve for unknown angles. For instance, if triangle ABC has angles A and B with known angles of 40° and 30° respectively, then the missing angle can easily be solved for using the direct substitution principle. Since the angles of a triangle must add up to 180°, the missing angle C must equal 180° - 40° - 30° = 110°.

In conclusion, direct substitution is an important principle which can be used to simplify equations and to solve for unknowns. This principle is especially useful in geometry, algebra and trigonometry when solving equations and finding unknowns.