## Simultaneous Equations

### Introduction

Two unknowns require two simultaneous eqns

### Simultaneous Equations

### 4x + 2y = 8 (1)

### 2x - 5y = 10 (2)

(2) × 2 gives

### 4x - 10y = 20 (3)

(1) - (3) gives

### 12y = -12

so

### y = -1

Substituting this into (1)

### 4x + 2(-1) = 8

### 4x + -2 = 8

### 4x = 10

### x = 2.5

check that these values of x and y actually satisfy the two given simultaneous equations (witha all algebaraic equations, you can always check to see whether you have the right answer).