A community for students.
Here's the question you clicked on:
 0 viewing
anonymous
 5 years ago
help with...4x^2+8x21=0
anonymous
 5 years ago
help with...4x^2+8x21=0

This Question is Closed

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0do you know the quadratic formula?

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0ok we can try to factor it then

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0yeah thats what im doing..i have to factor it

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0a=4, b=8, c=21 Find factors of a*c that add up to be b

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0right! a*c=4(21) play with this until you get the sum of the factors to be b=8 4+21 is not 8 a*c=12(7) 127 is not 8 a*c=6(14) is 614 =8?

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0but we want 8 how can we get 8

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0what if you said a*c=6(14) what is the sum of those two factors?

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0now replace the bx term with what you just found but you need an x behind each term so it equals bx

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0ohhh okay then you have to group it right?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0so then it would be(4x^2+14x)(6x21)=0 which then what?

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0what do 4x^2 and 14x have in common?____________ what do 6x and 21 have in common?___________

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.02x 3 so the first 2 terms we factor out 2x(2x+7) so the second 2 terms we factor out 3(2x+7) so 4x^2+14x6x21=2x(2x+7)3(2x+7) can we do anything else?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0yeha ohh aha i would have never thought of that..

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0then you do 2x3=0 and 2x+7=0..

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0there is 2x+7 in both of those two terms above so we can factor a 2x+7 out of both giving us (2x+7)(2x3) this expression was orignally set =0 so we have (2x+7)(2x3)=0 so either 2x+7=0 or 2x3=0 when i say both its the exclusive kind

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0you got that part? was the factoring the problem you were having?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0then the answer is x=2/3 and x=2/7!!

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0omg thanks soo much for your help!! haha sorry that took me forever to figure out:/ thanks though!

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0x=2/3 is right but x=7/2 for the second one
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.