Question

i just need the answer choice. I know how to get it. just not sure.
Solve. 3x2 = -15x + 21
answer choices:
the quantity of negative 5 plus or minus i square root 3 all over 2
the quantity of 5 plus or minus square root 53 all over 2
the quantity of 5 plus or minus 3 square root 3 all over 2
the quantity of negative 5 plus or minus square root 53 all over 2

Answer 1

1. Get it equal to 0
2. Divide both sides by 3
3. Identify a, b, and c
4. Plug into the quadratic ormula.

Answer 2

which one is it though...?

Answer 3

Follow those steps. Do you need help doing so?

Answer 4

Those steps are exactly how we would find the answer to give to you, so why don't you do it and get the practice?

Answer 5

When you completed step 4, that would be your answer.

Answer 6

Show your work for step 4, then we can analyze your problem.

Answer 7

okay, question, do I put the right side equal to zero or he left?

Answer 8

The right.

Answer 9

okaaaay..x=7/5?

Answer 10

Could you show how you got that?

Answer 11

-15x+21=0
15x=-21
x=7/5

Answer 12

You misunderstood the directions: you need to rearrange the equation so that everything is the left, and 0 on the right. You still have all three terms!

Answer 13

OHHH! thanks!

Answer 14

:-)

Answer 15

so its going to be 3x^2+15x-21=0

Answer 16

yes

Answer 17

then what do I do?

Answer 18

Step 2

Answer 19

Now you have your quadratic in the form desired: ax^2+bx+c = 0. plug values into quadratic formula

\[x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}\]

Answer 20

Make your life simpler and divide both sides by 3 first.

Answer 21

do I not simplify them because they are divisible by 3..?

Answer 22

you can if you want. makes no difference to the answer.

Answer 23

so I got s(x^2+5x-7)=0

Answer 24

supposed to be a 3 in the begining

Answer 25

yeah. so now your values of a,b,c are?

Answer 26

a=3
b=5
c=-7?

Answer 27

a=1

Answer 28

you divide by 3 to get rid of that leading 3...

right, a = 1, b = 5, c = -7

Answer 29

thanks so much! I got it!

Answer 30

which choice is the correct answer?

Answer 31

D

Answer 32

very good!

Answer 33

:)!!!!!!!!

Answer 34

go forth and solve many quadratics :-)

Answer 35

enjoy the fact that you get that nice, simple formula to use. It all goes out the window when you start doing x^3...