Exercise 12 Page 247

Substitute -4 for r in the expression. When dividing real numbers, the quotient will be positive if the signs are the same and it will be negative if the signs are different.

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Practice makes perfect

To evaluate the given expression for r=-4, first, we should substitute -4 for r in the given expression and simplify.

8-r/-2

Substitute

r= -4

8-( -4)/-2

SubNeg

a-(- b)=a+b

8+4/-2

AddTerms

Add terms

12/-2

When dividing real numbers, the quotient will be positive if the signs are the same and it will be negative if the signs are different.

cc Same Sign & Different Signs (+)÷(+)=(+) & (+)÷(-)=(-) (-)÷(-)=(+) & (-)÷(+)=(-) In our case one number is positive and one number is negative, so the quotient will be negative.

12/-2

MoveNegDenomToFrac

Put minus sign in front of fraction

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CalcQuot

Calculate quotient

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We can verify this using a calculator.