Question

how to factor this equation 5v^2-50v+105=0 ? or x^2+8x+16=0 I'm not to good at factoring any help

Answer 1

Well for the first one start by factoring out a 5 to get 5(v^2-12+21) Let me know if ya need help after that.

The second one, you can just factor straight away. For this second one look for a term whose product equals positive 16 and sum equals a positive 8.

Answer 2

the problem i have with them is when you get to (x ) (x ) i get confused what to do next with them

Answer 3

Ah ok. When you get to (x )(x ) you will be using the F.O.I.L. method which stands for first, outer, inner and last. This means you take the first two terms and multiply them, then you take the outer two terms and multiply them, etc.

For example with your first problem you have 5(v^2-10x+21). The first thing you want to look for is what number multiplied by what will give me positive 21. AND those two numbers you pick need to add up to -10 in this case.

So your answer would be -7 and -3. Which gives you this as your final answer. 5(x-7)(x-3)

So for F.O.I.L. it would look like this. For this "first" terms you would take x multiplied by x giving you x^2. The "outer" terms would be x and -3 giving you -3x. The "inner" terms would -7 and x giving you -7x. The "outer" terms would be -3 and -7 giving you positive 21. Which gets you from (x-7)(x-3) BACK to your original expression of (x^2-10x+21) or in this case you would be using the letter v instead of x.

Answer 4

but what do you do with the 5 on the outside ?

Answer 5

That is just a part of the final answer. When you simplify an expression like that down to its roots you set each part equal to zero like this. x-7=0, x-3=0, and 5=0. Since 5 does not equal zero it is extraneous. but the other two turn out to be X=7 and X=3 which are the roots or x-intercepts of the expression