Algebra: Chapter 10-2, p 436
Multiplying Rational Expressions
To multiply rational numbers, we multiply the numerators and multiply the denominators. We multiply rational expressions in the same way.
For example, we have the following 2 examples:
`(–2)/(2y+6)*3/(y–5)=(-2*3)/((2y+6)(y-5))=(-2*3)/((2)(y+3)(y-5))=(-3)/((y+3)(y-5))` and
`4/(5x^2)*(x-2)/(2x^3)=(4(x-2))/(10x^5)=(2(x-2))/(5x^5)`
Here is a link from purplemath.com as well with more information and examples.
Math-8, Chapter 9-10, p 472
Percent of Change
Percent of change is covered by the simple formula:
`(New – Old)/(Old)`
INCREASE is a POSITIVE value and DECREASE is a NEGATIVE value.
The book does is some other way, but I think this formula is EASIER!
For example, “find the percent of change from 120 to 135”. Using the formula, we have:
OLD = 120, NEW = 135, or … `(135-120)/(120) = 15/120 = 0.1250`
0.125 becomes 12.5% using D2P!