Questions on Algebra: Inverse operations for addition and multiplication, reciprocals answered by real tutors!

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Question 132658: Please help.
1.Solve these using the multiplication principle.
9x = 90
-x = 42
-x/4 = 11
-3/5x = 12/35
: Please help.
1.Solve these using the multiplication principle.
9x = 90
-x = 42
-x/4 = 11
-3/5x = 12/35

Answer by jim_thompson5910(9166) About Me  (Show Source):
You can put this solution on YOUR website!
I'll do the first two to get you started

# 1


9x=90 Start with the given equation



(1/cross(9))cross(9)x=(1/(9))90 Multiply both sides by 1/9 to isolate x. Note: 1/9 is the multiplicative inverse of 9



x=90/9 Multiply


x=10 Divide

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Answer:
So our answer is x=10






# 2



-x=42 Start with the given equation



(-1/cross(1))cross(-1)x=(-1/(1))42 Multiply both sides by -1/1 to isolate x. Note: -1/1 is the multiplicative inverse of -1



x=(-42)/1 Multiply


x=-42 Divide

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Answer:
So our answer is x=-42