Exercise 34 Page 9

Use the Multiplication Property of Equality.

y=-10

Practice makes perfect

To solve the given equation for y, we need to isolate it by multiplying both sides of the equation by - 52. We want to multiply by - 52 because it is the reciprocal of - 25. This is allowed by the Multiplication Property of Equality.

-2/5y=4

MultEqn

LHS * (-5/2)=RHS* (-5/2)

-5/2(-2/5y)=-5/2* 4

MultNegNegOnePar

- a(- b)=a* b

5/2*(2/5y)=-5/2* 4

AssociativePropMult

Associative Property of Multiplication

(5/2*2/5)y=-5/2* 4

MultFracByInverse

a/b* b/a=1

1* y =-5/2* 4

IdPropMult

Identity Property of Multiplication

y=-5/2* 4

MoveRightFacToNum

a/c* b = a* b/c

y=-5* 4/2

Multiply

y=-20/2

CalcQuot

Calculate quotient

y=- 10

We will check our solution by substituting this result back into the original equation and simplifying. If doing so results in an identity, our solution is correct.

-2/5y=4

Substitute

y= -10

-2/5( -10)? =4

MultNegNegOnePar

- a(- b)=a* b

2/5* 10? =4

MoveRightFacToNum

a/c* b = a* b/c

2* 10/5? =4

Multiply

20/5? =4