Question

What are the approximate solutions of 2x2 − 7x = 3 rounded to the nearest hundredth?

No real solutions

x ≈ −0.77 and x ≈ 7.77

x ≈ −0.39 and x ≈ 3.89

x ≈ −3.89 and x ≈ 0.39

Answer 1

rewrite the equation

\[2x^2 - 7x - 3 = 0\]


use the general quadratic formula

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

in your question a = 2, b = -7 and c = -3

evaluate to 3 decimal places for your answer

Answer 2

what do you mean by "evaluate to 3 decimal places for your answer"?

Answer 3

three places after the decimal sign

Answer 4

so i plug in thhose numbers into that equation?? and then when i have the answer i bring it 3 decimal places to the right?

Answer 5

substitute the numbers and then get you answers to 3 decimal places

Answer 6

thats it remember there are 2 answers.....

Answer 7

http://www.purplemath.com/modules/rounding.htm
should be 2 places for hundredth

Answer 8

I think the 3rd option will be close to the answer... just doing some mental arithmetic

Answer 9

oops.. you only need 2 decimal places.... I just re-read the question

Answer 10

i did it..but i came out with a weird equation....

Answer 11

do you have radicals in your answer..?

Answer 12

you need to find the value of

\[x = \frac{7 + \sqrt{73}}{4}... and ... x = \frac{7 - \sqrt{73}}{4}\]

Answer 13

7+- squared 25
----------------
4

Answer 14

wait how did you get 73??

Answer 15

ok... a couple of things you need to put the -7 in brackets before squaring

\[\sqrt{(-7)^2 - 4 \times2\times-3} = \sqrt{49 + 24} = \sqrt{73}\]

Answer 16

calcuators see the negative as an operator.... and not as part of the number

Answer 17

-4 times 2 would be 8? then 8 times -3 would get what though?

Answer 18

-4 x 2 = -8 -8 x -3 = 24

Answer 19

yeah so itsnt it 24 not 73?

Answer 20

. thats it

Answer 21

oh pellet nvm!! i see you add the 49

Answer 22

yes... -7 x -7 = 49

Answer 23

so then what do we do after that?

Answer 24

ok so you have \[x = \frac{7 + \sqrt{73}}{4}\]

get a value for this correct to 2 decimal places

then get a value for

\[x = \frac{7 - \sqrt{73}}{4}\]

Answer 25

how do i even put that into a decimal?

Answer 26

in your calculator just type the numerator and press equals...


then its answer divided by 4

if you have a graphing calculator you may need 2nd = to get the decimal approximation

the answers are 3.89 and 0.39

Answer 27

thank you!!

Answer 28

but wait there has to be one negative cause thats not an answer...

Answer 29

so is it C?

Answer 30

3.886
-.386

Answer 31

all the work above is correct, just dropped sign on .386

Answer 32

oops yes... I missed a negative

Answer 33

alright so it is answer C? thats what you guys are saying...

Answer 34

yes thats what we are saying