2 - Group 4 - Subtraction of Fractions Scripts
- 1. Subtraction of fraction What’s a lot like addition. Like an addition, just remember that the denominators always must be the same. Let’s try three over four minus one over four. Let’s look at a square, cut into four pieces. Three pieces will be Because we want to do three over four minus one over four, we can take away one over four that is one piece. We are left with two pieces. So, three over four minus one over four equals Two over four. But, look what we really did. We just subtracted the numerators. We can reduce two over four to an half. Now, let’s do one without pictures. Five over six minus four over six equals how much? Numerator will be five minus four and the denominator will be six, which is equal to one over six. Therefore the answer will be one over six. Now, let’s try and subtract two fractions which have different denominators. One over three minus two over seven. The LCM will be, hmmm twenty one. One over three will become one multiplied by seven over three multiplied by seven which equals seven over twenty. Two over seven will become two multiplied by three over seven multiplied by three which equals six over twenty one. Thus, seven over twenty one minus six over twenty one will be seven minus six over twenty one equals one over twenty one.
- 2. Let’s try one more. Take two over three minus one over nine. Here, we have to find the common the denominator which is the LCM. The LCM of three and nine is nine. Therefore the denominator for both of fractions will be nine. Change the first number two over three so that it has nine as the denominator. You can do two multiplied by three over three multiplied by three equals six over nine. And for the second number, one over nine, you don’t need to change the number because the denominator of this number is nine. And the numbers will be six over nine minus one over nine. Six minus one over nine equals five over nine. Therefore five over nine will be our answer.