Question

Use the quadratic formula to solve the equation:
3x^2-7x=5
use radicals as needed, express complex numbers in terms of i

Answer 1

do you know delta operator ?

Answer 2

no...

Answer 3

ok i will do without ^^

Answer 4

first step is :
\[3 * (x^{2} - 7 / 3*x -5/3) = 0\]

Answer 5

after that you have to do a little trick, it is based on :

(x - a)^2 = x^2 -2*a*x + a^2
do you know the trick ?

Answer 6

no

Answer 7

okay, so you have to make the x^2 disappear because we don't know what to do with it

Answer 8

\[3*( (x-7/6)^{2} -5/3 - (7/6)^{2})=0\] is the way to do it

Answer 9

because (x - 7/6)^2 = x^2 - 7/3x + 7/6 ^2

Answer 10

first step=subtract 5 from both sides

Answer 11

The problem specifically requires you use the quadratic formula, I suggest you do so. The quadratic formula is:\[-b \pm \sqrt{b ^{2}-4ac}\over2a\] where a is the coefficient of x^2, b is coefficient of x and c is the constant, the the quadratic is placed in standars form:\[ax ^{2}+bx+c=0\] Have you used the quadratic formula before?

Answer 12

dont see where the 'i' would come into place since youre not taking the root of a -

Answer 13

if u graph it does intersect with the x-ax

Answer 14

i think there are plenty of those exercise and the text is the same for the other

Answer 15

no c= -5

Answer 16

yes but she said she didn't jnow the delta operator :s

Answer 17

\[3x ^{2}-7x=5\] Placing it in standard form\[3x ^{2}-7x-5=0\]a=3, b=-7, and c=-5
Just plug these values in the formula and solve.

Answer 18

\[\frac{7\pm\sqrt{7^2-4\times(3)\times5}}{2\times3}\]

Answer 19

so wouldnt it be -7 +or- the sqrt of 109. take ans and divide by 6

Answer 20

There it is, with the numbers plugged in. What more could you ask for?

Answer 21

to understand ?

Answer 22

yea just plug in accordingly to formula

Answer 23

aha it's so meaningless : use the formula T_T

Answer 24

That was the purpose of the problem, learn to read and do.

Answer 25

Look at the top of this page and you will see her work instructed to use the quadratic formula, not competeing the square, or factoring.

Answer 26

yes, but so, why don't she knows the delta operator ? you don't learn it ?

Answer 27

somehow site is very slow. i had a typo but you are right, it is
\[x=\frac{7\pm\sqrt{109}}{6}\]sorry it took a while
delta operator?

Answer 28

ow okay
hum sorry for that, delta is b^2 - 4*a*c in france :s because it's use for two variables equations as well ^^"

Answer 29

well i guess we used it right?

Answer 30

Is that what we call the discriminate?

Answer 31

yep, but i asked her if she knew it :) she didn't because it hasn t a name for her, so i thought she wanted the calculus

Answer 32

yes it is discriminant or delta in french

Answer 33

She has moved on. So maybe later.

Answer 34

Wow, what a mess under this problem. It seems those with less experience who are providing me answers today are providing me wrong answers :( Perhaps I'll wait for the heros and legends and such from now on...

Answer 35

all the answer are gool ;) mine is without the formula, so it's not what you wanted sorry ;), the one of satellite is a good one.

(else you can learn your formula, it's an exercise to see if you know your lesson :) )

Answer 36

good *