Pearson Algebra 1 Common Core, 2011
PA
Pearson Algebra 1 Common Core, 2011 View details
4. Applications of Linear Systems
Continue to next subchapter

Exercise 27 Page 392

The a-variable represents the tens' place digit and the b-variable represents the ones' place digit.

37

Practice makes perfect

We are given a way to look at the value of a number so that the a-variable represents the tens' place digit and the b-variable represents the ones' place digit. Let's create equations from each of the given clues.

First Verbal Expression First Algebraic Expression Second Verbal Expression Second Algebraic Expression
The ones' place digit is b= The value of the number is 10a+b=
One more than... ...+1 Two more than... ...+2
Twice the tens' place digit 2a Five times the ones' place digit 5b
b=2a+1 10a+b=5b+2
We now have two equations and two variables. This means we can create and solve a system of equations. b=2a+1 10a+b=5b+2 Let's start by moving the b terms of the second equation to one side. We will then use the Substitution Method since the first equation already has the b-variable isolated.
b=2a+1 & (I) 10a+b=5b+2 & (II)
b=2a+1 10a-4b=2
b=2a+1 10a-4( 2a+1)=2
b=2a+1 10a-8a-4=2
b=2a+1 2a-4=2
b=2a+1 2a=6
b=2a+1 a=3
Now, that we have isolated the a-variable, we can substitute its value into the first equation and solve for b.
b=2a+1 & (I) a=3 & (II)
b=2* 3+1 a=3
b=6+1 a=3
b=7 a=3
We now know that there is a 3 in the tens' place and a 7 in the ones' place, so the value of the number is 37.