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Day 2 : Balance Method - both sides.Description: More practice balancing expressions with a variable parts in the LHS and RHS expressions
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Objective: The purpose of this exercise is to continue practicing balancing expressions. Remember that whatever you do the LHS expression you do the same to the RHS expression. Keep the idea of UNDOING in your mind. So to undo a -6 you ADD 6. To undo a multiplication you do a division. And remember, you generally UNDO everything in the reverse order. You UNDO adding and subtracting first and then UNDO multlying.
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08.010 Equations.On Both Sides (Sub)

Evaluate a where :
     6a - 7 = 5a + 2

This question is done exactly the same way as the previous question with an equation where expression 1 = expression 2

We solve it using the balance method  and UNDOing what we have done at each step.

6a -7 = 5a + 2

UNDO  subtracting 7 by adding 7 (on the Left Hand Side) and then do the same on the right hand side (add 7)

6a -7 + 7 = 5a + 2 + 7

 6a = 5a + 9

UNDO the adding of 5a to the right hand side by subtracting it from both sides.

6a - 5a = 5a - 5a + 9

   1a  = +9

Find a by dividing both sides by the co-efficient of 'a'

1a/1 = 9 / 1

a = 9.

(Obviously you don't have to divide by 1, but in general you UNDO the co-efficient of 'a' multiplied by 'a' .  UNDOing a multiplication is a division.

Check your answer

6a -7 = 5a + 2

6 x 9  -7  = 5 x 9 + 2

54 - 7 = 45 + 2

47  = 47

True - so we have the correct value of 'a' (9)  to make those two expressions equal.