## anonymous 5 years ago There are some binomials that can be expanded directly by a general inspection. For example (x+a)(x+b)=x^2+x(a+b)+ab. Can you recognize to which case the following expression belongs? (3x+7)(7x-3)

1. anonymous

$3\times7 \times(x+(7/3))\times(x-(3/7))$if you really wanted to , then you could express it as :$( 3 (x+(7/3) ) (7 (x-(3/7) ) )$ and then use the formula then take out the constant factors to get

2. anonymous

lol the first line of the last post be under the third line , if you get what I mean lols. Nevertheless, it is much easier to just expand it as a binomial straight away ie get 21x^2 -9x +49x -21 , and collect terms

3. anonymous

Are you using the foiling method? There are some binomial that can be multiplied and the answer can be found at a first glance. Like the example I gave you at the first line.

4. anonymous

Can you recognize what case does this example belongs to? According with wikipedia, there is not such a case. But we end up with a ax^2+bx+c expression.