3(2x+6) E) 9x-3 < 12 or 6x+2>-10 C)& 17<4x+5<21 F) 5(x-1)≤5x-3 Let's'>

Big Ideas Math Integrated I, 2016
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Big Ideas Math Integrated I, 2016 View details
Cumulative Assessment

Exercise 3 Page 98

Solve each inequality separately.

At Least One Integer Solution No Integer Solutions
5x-6+x≥2x-8
9x-3<12 or 6x+2>-10
5(x-1)≤5x-3
2(3x+8)>3(2x+6)
17<4x+5<21
x-8+4x ≤ 3(x-3)+2x
Practice makes perfect

We are asked to place each inequality in the correct box. Let's begin by naming each one of the inequalities. A)& 5x-6+x≥2x-8 D) x-8 +4x ≤ 3(x-3) + 2x B)& 2(3x+8) > 3(2x+6) E) 9x-3 < 12 or 6x+2>-10 C)& 17<4x+5<21 F) 5(x-1)≤5x-3 Let's solve each of them separately!

Inequality A

We can solve this inequality by performing inverse operations until we isolate the variable x.
5x-6+x≥2x-8
Solve for x
5x+x ≥ 2x-2
6x≥ 2x-2
4x≥- 2
x≥- 2/4
x≥ - 1/2

All numbers greater than - 12 are solutions to the inequality. Therefore, any integer greater than this number is a solution, such as x=1 or x=2.

Inequality B

We should start solving this inequality by distributing 2 and 3 inside the parentheses.
2(3x+8)>3(2x+6)
Solve for x
6x+16>3(2x+6)
6x+16>6x+18
16 ≯ 18
Since 16 is never greater than 18, there is no solution to this inequality. This includes any possible integer solutions.

Inequality C

This compound inequality can be solved by applying inverse operations on all three sides of the inequality.
17<4x+5<21
Solve for x

Subtract 5 from each expression

12<4x<16

Divide each expression by 4

3
This means that x cannot be an integer because the solution set consists of all values between two consecutive integers.

Inequality D

Let's try to isolate x in this inequality.
x-8+4x ≤ 3(x-3)+2x
Solve for x
x-8+4x ≤ 3x-9+2x
5x-8 ≤ 5x-9
-8 ≰ -9
Since 8 is not greater than or equal to 9, there are no solutions to this inequality. This includes any integer solutions.

Inequality E

Since this is an or compound inequality, we will solve each of the inequalities separately and then combine the solutions.
9x-3<12
Solve for x
9x<15
x<15/9
x< 1.66666...
x<1.67
So far we have that x<1.67. Since the original inequality is an or inequality we can already tell that it has at least one integer solution. For example, x=1 satisfies the first inequality and this is enough.

Inequality F

Let's start by distributing 5 inside the parentheses.
5(x-1)≤5x-3
Solve for x
5x-5 ≤ 5x-3
-5 ≤ -3
5 ≥ 3
Because 5 is always greater than 3, we have reached an identity. The solution to this inequality is all real numbers. Therefore there is at least one integer solution.

Conclusion

Finally, we can fill in the table with the information we have found.

At Least One Integer Solution No Integer Solutions
5x-6+x≥2x-8
9x-3<12 or 6x+2>-10
5(x-1)≤5x-3
2(3x+8)>3(2x+6)
17<4x+5<21
x-8+4x ≤ 3(x-3)+2x