how do you know when to give a decimal answer? the instructions will tell you what decimal position...
TRANSCRIPT
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.
636
7366 ...142857143.5
2-2 Solving Equations Using Addition and
Subtraction
Algebra 1 Glencoe McGraw-Hill Linda Stamper
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. 4012x 1
What equation is shown on the scale?
7 4x
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.
4 4x 3
The value or values of the variable that make the statement true is the solutionsolution to the equation.
x
What equation is shown on the scale?
5 2x
To isolate the variable, add 2 to create zero pairs. Keep the equation in balance and add 2 to the other side.
2 2x 7
The value or values of the variable that make the statement true is the solutionsolution to the equation.
x
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.
4012x Use inverse property.
12 1228x Simplify.
4012x 4012
4040
3215x 15 15
47x
3215x 3215
3232
28 47
? ?
Remember: In algebra work
downward. Line up the equal signs.
Skip one line after the answer.
Formally check even numbered homework problems.
Example 1
Check
50m27
27
23m
27
50m27 5027
5050
?
Solve.Example 2
Check
23c40
23 c1723
23c40 2340
04 04
231740
17
?
Example 3
Check
81
43
g
43
87
g
43
81
43
g
81
43
81
81
81
87
87
?
86
86
23
Example 4
Check
6.14x7.147.28
14.6x58
6.1458
?
Solve.Example 5
Check
1.8m9.24 8.1
m8.16 1.8
1.8m9.24 1.89.24
9.249.24
8.16
?
Example 6
Check
32
54
y
54
152
y
54
32
54
y
32
54
32
1510
32
152
152
?
1512
1512
6.14x4.43
6.14x7.147.28
6.147.147.28 4.434.43
1510
32
32
Ex. 7 Twenty-seven less than a number is negative sixty. 60 27n
27 33n 27
=
Write an equation and then solve.
Ex. 8 Negative fifty eight is the sum of a number and the opposite of twenty-nine.
29n58
92n29
29n58 29
=
2-A4 Page 82 #13-30,33-40. Formally check even numbered homework
problems.