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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 48 Page 57

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

Between 4 and 5.

Practice makes perfect

We want to use a table to find the two consecutive integers between which the solution lies for the given equation. -115b+80=-489 To choose a good starting point, let's pretend that the equation is a bit more simple.

-115b=-489 What multiplied by -115 would get us close to -489? This isn't the easiest thing to calculate in our heads, but it may be easier to get that - 115 * 5=-575. Let's start our table at b=5 and work up from there.

b	-115b+80	Evaluate
5	-115 (5)+80	-495
4	-115 (4)+80	- 380

Since our equation is -115b+80=-489, and -495<-489<-380, we know that the solution must lie between 4 and 5. 4

Subchapter links

Lesson Check p.56

Practice and Problem-Solving Exercises p.56-58

Standardized Test Prep p.58

Mixed Review p.58