Question

Do I have to put a trinomial in parentheses to factor it?

Answer 1

I'm not sure what you mean. Can you give an example?

Answer 2

My question is asking to complete the square of -5x^2 - 70x

I start by going -5(x^2 + 14x)
-5(x^2 + 14x + 49 - 49)
-5((x+7)^2 - 49)
-5(x+7)^2 + 245

Answer 3

Is that incorrect? the book says

-5(x^2 + 14x)
-5[(x^2 + 14x + 49) - 49]
-5[(x+7)^2 - 49]
-5(x+7)^2 + 245

Answer 4

So my question is do I have to put the trinomial in parentheses to factor it?

Answer 5

your third step -5((x+7)^2 - 49) is exactly the same as the books third step -5[(x+7)^2 - 49], it's just using brackets instead of parenthesis

Answer 6

so there's no major difference between your answer and the book's answer

Answer 7

But my second steps are different

Answer 8

Which second step is correct?

Answer 9

-5(x^2 + 14x + 49 - 49) is equivalent to -5((x^2 + 14x + 49) - 49)

Answer 10

since x^2 + 14x + 49 is the same as (x^2 + 14x + 49)

Answer 11

Why did they place x^2 + 14x + 49 in parenthesis? They did that to show that they're going to factor it to get (x+7)^2. But parenthesis are not necessary.

Answer 12

I see so x^2 + 14x + 49 = (x+7)^2 and (x^2 + 14x + 49) = (x+7)^2 ?

Answer 13

@jim_thompson5910

Answer 14

exactly, they are the same

Answer 15

the parenthesis are just a visual aid to help see how the terms factor

Answer 16

Can you tell me why -5(x^2 + 14x + 49 - 49) is equivalent to -5((x^2 + 14x + 49) - 49)

Answer 17

because placing parenthesis around x^2 + 14x + 49 does NOT change the expression

Answer 18

it's merely done to group the terms and show how/why they got (x+7)^2

Answer 19

Okay thanks

Answer 20

yw

Answer 21

@jim_thompson5910
In
-5((x^2 + 14x + 49) - 49) nothing happens inside the nested brackets right? so you can pretend they don't exist right?

Answer 22

yes, that's a good way to put it

Answer 23

they're only there to put extra focus on x^2 + 14x + 49 (ie so you can see it better)