Big Ideas Math Integrated I, 2016
BI
Big Ideas Math Integrated I, 2016 View details
1. Solving Simple Equations
Continue to next subchapter

Exercise 49 Page 10

Practice makes perfect
a First, let's isolate x on the left-hand side.
ax=b-5
x=b-5/a
Now, we can substitute each of the integers for b and check the value of the numerator.
b b-5/a Simplify
- 2 - 2-5/a - 7/a
5 5-5/a 0/a
9 9-5/a 4/a
10 10-5/a 5/a

Right away we can disregard - 2 and 5 as values of b. Inputting these values resulted in fractions that will not give a positive quotient when dividing by any of the remaining integers. We only have two options now. b=9 or b=10 From the numbers available, 4 is only divisible by - 2, but this would result in a negative quotient, so we can disregard b=9. Dividing 5 by 5 equals 1, a positive integer! Therefore, a=5.

When a= 5 and b=10, x is a positive integer.

b From Part A, we know that substituting the various values for b gives us the following fractions.
- 7/a, 0/a, 4/a, and 5/a

Again, we can disregard the first two fractions, they will not give us a negative integer when substituting any of the remaining values for a. This leaves us with two options. b=9 or b=10 Since we are looking for a negative quotient, we are going to need a negative denominator, which must be a=-2. The only numerator that is divisible by - 2 is 4. Therefore b=9.

When a= - 2 and b=9, x is a negative integer.