Explanation
Multiplication and substitution is a technique often used in algebra, particularly for solving systems of linear equations and manipulating algebraic expressions.
Multiplication
Multiplication involves scaling an equation or an expression by a constant factor. Here, the idea is to multiply both sides of an equation by the same non-zero constant to simplify or adjust coefficients. For example, consider the equation:
ax+by=c
Multiplying both sides by a constant k gives:
k(ax+by)=kc
Substitution
Substitution involves replacing a variable with an equivalent expression from another equation. This method is especially useful when dealing with systems of equations. Consider the system of equations:
- x+y=5
- 2x−y=3
First, we can solve the first equation for y:
y=5−x
Next, we substitute this expression for y in the second equation:
2x−(5−x)=3
Simplifying this equation:
2x−5+x=3
3x−5=3
3x=8
x=38
Then, we substitute back to find y:
y=5−38
y=315−38
y=37
Thus, the solution to the system is:
x=38,y=37
Key Points
- Multiplication is used to adjust the coefficients of equations.
- Substitution is used to eliminate variables by replacing them with expressions from other equations.
- These methods are often applied in tandem to simplify and solve systems of equations.