Section 1.4

Writing Equations and Inequalities

Open Sentence: Math statement which contains two algebraic expressions and the symbol comparing them.

=        to equal; be equivalent; same

>        greater than; more than

        greater than or equal to; at least; no less than

<        less than; fewer than

        less than or equal to; at most; no more than

Equations: An open sentence containing an equals sign.

Inequalities: An open sentence containing >,  (Many possiblities)

        ex. 4 < x < 9

1.) The difference of twice a number w and 8 is 12.

        2(w) - 8 =  12

               + 8 = + 8

                2w = 20

                  w = 10

2.) A number y is no less than 5 and no more than 13.

        5  y  13

Solutions: The answer to a problem.

        ex. 3x + 7 = 15        Could 3 be the solution?

substitute 3 for x         3(3) + 7 = 15

                             9 + 7 = 16 15

NOT A SOLUTION

Mental Math: WRITE IT OUT!

        Fee: $25        Fee + 3 lessons: $70

        25 + 3x = 70

                3x = 45                $15 per lesson

                  x = 15