Maths Unit 9 – Forming & Solving Equations Solving equations with unknowns on both sides Decide which side of the equation has the highest number of unknowns. In the example above, 5x is larger than 3x. Remove the unknowns on the other side by completing the inverse operation. To do this in this example you need to subtract 3x from both sides. Now you can continue to balance the equation until you are left with the value of the unknown. Solving equations The balancing method can be used to solve equations as equations are like having a weighted scale which is balanced. If you take something off one side of the scale you must take the same thing off the other side to keep it balanced. This is the same for equations. To solve an equation you have to find the value of the missing number which will be given a letter. In this example you would subtract 3 from both sides to find the value of x is 2. Solving equations with unknowns on one side Remember to do the inverse operation on both sides Forming Equations When forming equations you need to use the information given to write an expression equal to a value given or a value that you know from another mathematical fact e.g. in this example you should know that the sum of angles in a triangle is equal to 180°. Based on this fact we can form an equation and go on to solve it to find the actual sizes of each of the angles. Remember your inverse operations……… Adding is the inverse of subtracting Subtracting is the inverse of adding Multiplying is the inverse of dividing Dividing is the inverse of multiplying Square rooting is the inverse of squaring Squaring is the inverse of square rooting The equation….. 5a – 23 + 4a + 44 + 2a + 16 = 180 Simplify…… 11a + 37 = 180 -37 -37 11a = 143 ÷11 ÷11 a = 13 Key words and definitions Equation – a mathematical statement that has two things equal to each other. It consists of two expressions either side of an equals sign. Expression – in algebra this is a combination of terms