Pre-Algebra: Chapter 9-8
Percent and Estimation
To estimate percent, round the percent to the nearest 100, 10, 5 or some multiple of 5 or 10 (usually). Just give it your best shot, in that estimates are just approximations. Remember, to use whickity-whack divide and D2P when you need them
Algebra: Chapter 10-6
Solving Rational Expressions
We are now solving rational equations, they have an equal sign. With rational expressions on both side, we can sometimes structure these as ratios or proportions. We can solve proportions by criss-crossing, if a ÷ b = c ÷ d, then ad = bc. We just plug in the numerators and denominators where apprpriate and work it out.
Remember too, that a quadratic equation has 0, 1 or at most 2 roots or answers. Sometimes, one of the solutions can be considered extraneous or invalid. Usually, it results in the denominator of an expression being = 0. In Algebra I, we don’t know how to handle that but eventually in higher math, you will.