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Pearson Algebra 1 Common Core, 2011

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Pearson Algebra 1 Common Core, 2011 View details

8. An Introduction to Equations

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Exercise 47 Page 57

Use mental math to guess the starting value for the table.

Between -5 and -4.

Practice makes perfect

We want to use a table to find the two consecutive integers between which the solution lies for the given equation. 3.3=1.5-0.4y To choose a good starting point, let's pretend that the equation is a bit more simple.

3.3=-0.4y What multiplied by -0.4 would get us close to 3.3? This isn't the easiest thing to calculate in our heads, but we can easily know that (-0.4) (-10)=4. Let's start our table at y=-10 and work up from there.

y	1.5-0.4y	Evaluate
-10	1.5-0.4(-10)	5.5
-9	1.5-0.4(-9)	5.1
-8	1.5-0.4(-8)	4.7
-7	1.5-0.4(-7)	4.3
-6	1.5-0.4(-6)	3.9
-5	1.5-0.4(-5)	3.5
-4	1.5-0.4(-4)	3.1

Since our equation is 3.3=1.5-0.4y, and 3.1<3.3<3.5, we know that the solution must lie between -5 and -4. -5

Subchapter links

Lesson Check p.56

Practice and Problem-Solving Exercises p.56-58

Standardized Test Prep p.58

Mixed Review p.58