Core Connections Algebra 1, 2013
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Core Connections Algebra 1, 2013 View details
2. Section 6.2
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Exercise 60 Page 272

Practice makes perfect
a To find the missing numbers, let's identify the variables using our variable diamond and substitute the correct numbers into our pattern.
Here, we are given that C=- 25 and B=5. Substituting these values into our pattern gives us the following equations. - 25&=A * 5 D &= A+ 5 From the first equation, we can calculate A by isolating it on one side.
- 25=A * 5
- 25 = 5A
- 25/5=A
- 25/5=A
- 5=A
A=- 5
We found A. We can substitute it into the second equation to find D.
D=A+5
D= - 5+5
D=0
Now we can complete our first diamond.
b In this part of exercise we are given values for A and B and we want to find C and D.
A= 8 and B=- 2To do this we can substitute the numbers into our pattern.
C= A * B & (I) D=A+B & (II)

(I), (II): A= 8, B= - 2

C= 8 * ( - 2) D= 8+( - 2)
C=- 16 D=8+(- 2)
C=- 16 D=8-2
C=- 16 D=6
We can now complete our second diamond.
c In this case we are given that B=6 and D=9. Substituting these values into our pattern gives us the following equations.
C&=A * 6 9 &= A+ 6 From the second equation we can calculate A by isolating it on one side.
9=A+6
3=A
A=3
We found A. Now, we substitute it into the first equation to find C.
C=A * 6
C= 3 * 6
C=18
We can complete our third diamond.
d Here we are given that C= - 20 and D=19. We want to find the numbers A and B.
- 20=A* B 19=A+B In this case, let's think of different pairs of numbers which multiply to give us - 20. Notice that when we multiply them we want to get a negative number. Therefore, we need a pair with one negative number. Multiplication of positive and negative numbers gives a negative number as a result.

&- 20=-1* 20 &- 20=-2* 10 &- 20=-4* 5 &- 20=- 20* 1 &- 20=- 10* 2 &- 20=- 5* 4 Let's check which, if any of these, will match the second condition as well. & -1+20=19 &-2+10=8 * &-4+5=1 * &-20+1=- 19 * &-10+2=- 8 * &- 5+4=- 1 * The pair A=- 1 and B=20 works for the pattern. Therefore, this is the correct pair of numbers to complete the diamond.

Notice that the pair A=20 and B=- 1 also works for the pattern. In this situation we have two possibilities to complete the diamond.