Mathematics 71 Online
OpenStudy (anonymous):

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

OpenStudy (anonymous):

do you know delta operator ?

OpenStudy (anonymous):

no...

OpenStudy (anonymous):

ok i will do without ^^

OpenStudy (anonymous):

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

OpenStudy (anonymous):

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 ?

OpenStudy (anonymous):

no

OpenStudy (anonymous):

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

OpenStudy (anonymous):

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

OpenStudy (anonymous):

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

OpenStudy (anonymous):

first step=subtract 5 from both sides

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?

OpenStudy (anonymous):

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

OpenStudy (anonymous):

if u graph it does intersect with the x-ax

OpenStudy (anonymous):

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

OpenStudy (anonymous):

no c= -5

OpenStudy (anonymous):

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

$3x ^{2}-7x=5$ 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.

OpenStudy (anonymous):

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

OpenStudy (anonymous):

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

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

OpenStudy (anonymous):

to understand ?

OpenStudy (anonymous):

yea just plug in accordingly to formula

OpenStudy (anonymous):

aha it's so meaningless : use the formula T_T

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

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.

OpenStudy (anonymous):

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

OpenStudy (anonymous):

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?

OpenStudy (anonymous):

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 ^^"

OpenStudy (anonymous):

well i guess we used it right?

Is that what we call the discriminate?

OpenStudy (anonymous):

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

OpenStudy (anonymous):

yes it is discriminant or delta in french

She has moved on. So maybe later.

OpenStudy (anonymous):

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...

OpenStudy (anonymous):

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 :) )

OpenStudy (anonymous):

good *

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