literal equations.pdf - INSTRUCTOR GUIDANCE EXAMPLE Week...

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Unformatted text preview: INSTRUCTOR GUIDANCE EXAMPLE: Week TWO Discussion [Please remerrber to use your own wording in your discussion. The writing here is intended to demonstrate the type of writing that is appropriate for a math discussion, and not intended for students to copy.] For this discussion we are to use Cowling “s R ule to determi ne the child sized dose of a particular medicine. Cowling“s Rule is a formula which converts an adult dose into a child“s dose using the child“s age. As in all literal equations this one has more than one variable, in fact it has three variables. T hey are a = child“s age Theformula is d = D(a +1) D = adult dose 24 d = child“s dose I have been assigned to calculate a 6-year-old chi ld“s dose of amoxicillin given that the adult dose is 500mg. d=flfl The Cowling"sRuleformula d = 5002:; + 1) I substituted 500 for D and 6 for a. d = $0253) Following order of operations I added inside parentheses first. d = fi) Following order of operations the multiplication comes next. d = 1338330 The division is the last step in solving for the chi ld“s dose. The proper dose of amoxicillin for a 6-year-old child is 146mg. The next thing we are to do for this discussion is to determine a chi ld"s age based upon the dose of medicine he has been prescribed. The same literal equation can be used, but we will just be solving for another of the variables instead of d. This ti me the adult dose is 1000mg and the chi ld“s dose is 208mg. I need to solve for a. d= D(a+ 1) The Cowling"sRuleformula 24 208 = 000(a + 1) I substituted 1000 for D and 208 for d. 24 It should be noted that once both values have been substituted in, the result is a conditional equation for which there is only one possible value for a to make it true. 208( 24) = 000(a + 1)(24) Both sides are multiplied by 24 to eliminate denominator. 24 4992 = 1000(a + 1) M ultiplication on left side is carried out. 4992 = 1000(a + 1) Divide both sides by 1000. 1000 —’l-999 4.992 = a + 1 One more step and it will be solved. 4.992 ' 1 = a + 1 ' 1 Subtract1 from both sides to isolate a. 3.992 = a We have solved for a. The dose of 208mg is intended for a four-year-old chi ld. ...
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