Page 57 - CalcBus_Flipbook

CH 6] Calculating Business 6-9

Since both members (right and left of =) are equal, the value calculated must be correct.

Example B: Solve for N and check: 0.2N = 6

Solution: N has been multiplied by 0.2. The reciprocal operation is employed to isolate N.
Therefore,
0.2N = 6
1
1
( / 0.2) (0.2) (N ) = (6) ( / 0.2) Multiplying both sides by the reciprocal. Check:
0.2
1
( / 0.2) (N ) = (6) ( / 0.2) Reciprocal of 0.2 is / 0.2 0.2 N = 6
1
6
(1) (N) = ( / 0.2) 0.2 (30) = 6
N = 30 Answer 6 = 6

2
Example C: Solve for N and check: / 3N = 6
2
Solution: N has been multiplied by / 3. The reciprocal operation is employed to isolate N.
Therefore,
2 / 3N = 6
3
3
2
( / 2) ( / 3) (N ) = (6) ( / 2) Multiplying both sides by the reciprocal. Check:
6
3
( / 6) (N ) = (6) ( / 2) Reciprocal of / 3 is / 2 . 2 / 3 N = 6
2
3
18
(1) (N) = ( / 2) 2 / 3 (9) = 6
N = 9 Answer 6 = 6

Example D: Solve for N and check: –2N = –8
Solution: As N is multiplied by –2, the reciprocal operation is used to isolate N. Therefore,

–2N = –8
1
1
( / -2) (–2) (N ) = (–8) ( / -2) Multiplying both sides by the reciprocal. Check:
1
-2
( / -2) (N ) = (–8) ( / -2) Reciprocal of –2 is / -2. –2N = –8
1
–8
(1) (N) = ( / -2) (–2)(+4) = –8 6
N = +4 Answer –8 = –8

Example E: Solve for N and check: –N = –1
Solution: –N = –1 Means
–1N = –1 The coefficient to a variable when not stated is fixed at 1 and in this
case is a –1. The relationship of –1 and N is multiplication.
1
1
( / -1) (–1) (N ) = (–1) ( / -1) Multiplying both sides by the reciprocal. Check:
-1
1
( / -1) (N ) = (–1) ( / -1) Reciprocal of –1 is / -1. –N = –1
1
–1
(+1) (N) = ( / -1) (–1)(+1) = –1
N = +1 Answer –1 = –1

———————— Rule to Remember —————————
Since in an equation the value of the left member is the same as the value of the
right member, what is done to the left side must also be done to the right side in order
to keep the equality of both sides.

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