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How do you know when to give a decimal answer? The instructions will tell you what decimal position you will need to round. Otherwise, if dividing does.

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Presentation on theme: "How do you know when to give a decimal answer? The instructions will tell you what decimal position you will need to round. Otherwise, if dividing does."— Presentation transcript:

1 How do you know when to give a decimal answer? The instructions will tell you what decimal position you will need to round. Otherwise, if dividing does NOT produce a positive or negative whole number (known as an integer), then leave the answer fractional, but in lowest terms.

2 2-2 Solving Equations Using Addition and Subtraction Algebra 1 Glencoe McGraw-HillLinda Stamper

3 To solve an equation means to find all the values of the variable that make the equation a true statement. One way to do this is to isolate the variable on one side of the equal sign. Change (transform) the original equation using equivalent equations. The basic rule when writing equivalent equations is: Whatever you do to one side of the equal sign, you must also do to the other side of the equal sign. Doing this maintains the equality of the equation. The equations in this chapter are called linear equations. In a linear equation the exponent of the variable is one. 1

4 What equation is shown on the scale? To isolate the variable, take away the 4, but to keep the equation in balance whatever you do to one side you must do to the other side. solution The value or values of the variable that make the statement true is the solution to the equation.

5 What equation is shown on the scale? To isolate the variable, add 2 to create zero pairs. Keep the equation in balance and add 2 to the other side. solution The value or values of the variable that make the statement true is the solution to the equation.

6 Two operations that undo each other, such as addition and subtraction, are called inverse operations. Inverse operations help you to isolate the variable on one side of the equal sign. Check   The problem. Use inverse property. Simplify. ? ? Remember: In algebra work downward. Line up the equal signs. Skip one line after the answer. Formally check even numbered homework problems.

7 Example 1 Check  ? Solve. Example 2 Check  ? Example 3 Check  ?

8 Example 4 Check  ? Solve. Example 5 Check  ? Example 6 Check  ?

9 Ex. 7 Twenty-seven less than a number is negative sixty. = Write an equation and then solve. Ex. 8 Negative fifty eight is the sum of a number and the opposite of twenty-nine. =

10 2-A4 Page 82 #13-30,33-40. Formally check even numbered homework problems.


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