OpenStudy (srtauser):

Solve. 3x2 = -15x + 21

1 year ago
OpenStudy (soprano.h.d0816):

Hey there!!! Since you are new here, read this tutorial for new OpenStudiers!! http://openstudy.com/study#/updates/543de42fe4b0b3c6e146b5e8 You might not have known, but you are in the "OpenStudy Feedback" section. Place your mouse over where it says OpenStudy Feedback, and find the correct subject by clicking the 'Find More Subjects' button or simply clicking the correct subject in the list that you have already studied! Please enjoy being on OpenStudy. And don’t forget to read OpenStudys’ Code of Conduct and also, OpenStudy's Terms and Conditions :D This section is for providing your Feedback/Appreciation regarding the site and by Feedback, we mean "helpful information or criticism that is given to someone to say what can be done to improve a product( which is the site in this case)" You can use this section: ⇝ If you want to appreciate to OpenStudy ⇝ To share your thoughts on how to improve OpenStudy ⇝ To inform the site about any difficulty you are facing while using OpenStudy ⇝ To ask any other question related to this site. ⇝ If you want to post any posts such as congratulating someone, saying Happy Birthday, etc. If you have any questions, please feel free to PM me or tag me in your post :D

1 year ago
OpenStudy (srtauser):

So i know what to do up until the point where my answer looks like 3x^2-15x-21=0

1 year ago
OpenStudy (soprano.h.d0816):

You need to add 21 to both sides

1 year ago
OpenStudy (srtauser):

then what? is it supposed to look like 3x^2-15x=21?

1 year ago
OpenStudy (soprano.h.d0816):

Yes. Now, 3x^2 is 9x-15x=21 ^^^^^^ Combine -6x = 21 --- --- -6 -6 x = ??

1 year ago
OpenStudy (srtauser):

-3.5

1 year ago
OpenStudy (srtauser):

what is that in a square root form?

1 year ago
OpenStudy (soprano.h.d0816):

Errr.... idk right off

1 year ago
OpenStudy (srtauser):

well my answer options are A. the quantity of negative 5 plus or minus i square root 3 all over 2 B. the quantity of 5 plus or minus square root 53 all over 2 C. the quantity of 5 plus or minus 3 square root 3 all over 2 D. the quantity of negative 5 plus or minus square root 53 all over 2

1 year ago
OpenStudy (soprano.h.d0816):

Errrr.....

1 year ago
OpenStudy (srtauser):

im stuck on it too

1 year ago
OpenStudy (soprano.h.d0816):

@agent0smith ??

1 year ago
OpenStudy (agent0smith):

3x^2-15x-21=0 From here, you can take out a common factor of 3.

1 year ago
OpenStudy (srtauser):

ok so 3(x-5x-7)=0

1 year ago
OpenStudy (srtauser):

I dont know what to do nexst because this trinomial can't be changed

1 year ago
OpenStudy (agent0smith):

You forgot the x^2 3(x^2-5x-7)=0 Now divide both sides by 3. You can't factor it, use the quadratic formula.

1 year ago
OpenStudy (srtauser):

then I get 5+_ sqrt 109 over 6

1 year ago
OpenStudy (agent0smith):

Keep in mind that you are using the quadratic formula for x^2-5x-7=0... it looks like you didn't do it for that.

1 year ago
OpenStudy (srtauser):

How do I do it for that then?

1 year ago
OpenStudy (agent0smith):

By using the quadratic formula. It looks you used 3(x^2-5x-7)=0 and not x^2-5x-7=0... meaning you did not divide both sides by 3.

1 year ago
OpenStudy (srtauser):

oh ok -5/3x-7/3=0 is this right?

1 year ago
OpenStudy (agent0smith):

3(x^2-5x-7)=0 When you divide both sides by 3, you do not touch anything inside the parentheses.

1 year ago
OpenStudy (srtauser):

so it is like i said before x^2-5x-7=0 or not?

1 year ago
OpenStudy (agent0smith):

Yes. Now use the quadratic formula.

1 year ago
OpenStudy (srtauser):

which is what I used before?

1 year ago
OpenStudy (agent0smith):

Then how did you get the "over 6" part? The denominator of the quadratic formula is 2a.

1 year ago
OpenStudy (srtauser):

oh ok. I see so it is (5+-√53)/2 Thank you so much!

1 year ago
OpenStudy (soprano.h.d0816):

He's very smart(:

1 year ago
OpenStudy (agent0smith):

Much better. And ty!

1 year ago
Similar Questions: