## Reciprocal-fraction

From Omilili

### Argh with the fractions...

Me! Thanks sooo much - this place is a godsend, I swear! One over a fraction is the reciprocal of that fraction, so Then if the denominator needs to be rationalized, you have Quote: : Err I could figure out how to enter this in TeX so it would look a little better?) 1. Num. 1 Den. 24/5 = 5

Question:my son has to show his work for his 5th grade math word problems. I have come up with the answer and can show him how to do it but I don't understand why the process is different and I would like to explain to him the difference. The math problem says that out of 96 singers 3/8 of them are tenors. How many are tenors? The answer is 36 according to his math book.- which is correct of course. To get to the answer I simply divided 96 by 8 and multiplied it by 3 which gives me 36. BUT- in other sections of his math book it tells him to use the reciprocal method to find the answer for dividing a whole number by a fraction. When should he simply divide the denominator into the whole number and then multiply it by the numerator versus using the reciprocal method (ie flip the fraction and multiply instead of divide by the whole number) to divide a whole number by a fraction? What is the difference and any suggestions for explaining this to a 5th grader

Answers:In this case you are not dividing by a fraction, you are multiplying: (3/8) * 96 = (3/8) * (96/1) = (3*96) / (8*1) The reciprocal method would apply is you had this kind of problem: 96 / (3/8) = 96 * (8/3) ===================== The first answer is very good - too many kids don't understand ratios. (but it doesn't really answer your question)

Question:I've been at this problem for who knows how long now.. I think I'm getting confused on factoring an equation that has a mixed number in its square. 3k^2-2k-1 9k^2-1 ---------------- / ------------------- 3k^2+14k+11 3k^2+8k-11 There are two fractions there and I know I have to take the reciprocal of the second fraction then multiply. I'm not sure how to factor the 3k^2 though. Ok, I was able to get my answer, but how do you factor a quadratic like: 3k^2 - 2k - 1 ?

Answers:Factorise each of the quadratics first 3k^2 - 2k - 1 = (3k + 1)(k - 1) 3k^2 + 14k + 11 = (3k + 11)(k + 1) 9k^2 - 1 = (3k + 1)(3k - 1) 3k^2 + 8k - 11 = (3k + 11)(k - 1) You will then find that when you invert the second fraction and multiply, some of the factors will cancel out leaving quadratics on top and bottom. These might as well be left in factorised form. EDIT. Factorising quadratics is really down to practise and experience. It is easier with numbers like 3 and 11 which can only factorise one way. Work on the k^2's and constants while trying to make the k term correct. Remember that not all quadratics factorise nicely.

Question:Please help. i'm doing my math hw and forgot how to add fractions lol. please hep. the question is .... 1/.5 + 1/6 I already know the answer is 2 and 1/6 i just need to know how to get the answer. i feel stupid lol. thanks for the help :) 10 points who shows me how.

Answers:1/.5 is the same as saying (1/1)/(1/2). in fraction division you multiply by the reciprocal so it is (1/1)x(2/1)=2/1=2. then you just throw the 1/6 in there and call it a day.

### Division of Fractions Taught Conceptually, part 2

Reciprocal numbers are taught by looking at measurement divisions with a dividend of 1 (eg 1 divided by 3/4). Then the procedure is generalized to any fractional dividend, so that we arrive at the common shortcut for division of fractions (the shortcut of flip and multiply). These steps effectively justify the rule for dividing fractions to the students.

### Solving Equations with Fractions - YourTeacher.com - Math Help

For a complete lesson on solving equations with fractions, go to www.yourteacher.com - 1000+ online math lessons featuring a personal math teacher inside every lesson! In this lesson, students learn to solve equations that involve fractions by either multiplying both sides of the equation by the reciprocal of the fraction, or multiplying both sides of the equation by the denominator of the fraction. The goal is to get rid of the fraction as soon as possible.

### Multiplying Fractions - YourTeacher.com - Math Help

For a complete lesson on multiplying fractions, go to www.yourteacher.com - 1000+ online math lessons featuring a personal math teacher inside every lesson! In this lesson, students learn to multiply two fractions by multiplying across the numerators, and multiplying across the denominators. Students learn to divide two fractions by taking the reciprocal of the second fraction, then multiplying the fractions.

### Multiplying Fractions - YourTeacher.com - Algebra Help

For a complete lesson on multiplying fractions, go to www.yourteacher.com - 1000+ online math lessons featuring a personal math teacher inside every lesson! In this lesson, students learn to multiply two fractions by multiplying across the numerators, and multiplying across the denominators. Students learn to divide two fractions by taking the reciprocal of the second fraction, then multiplying the fractions.

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