Question

I have no idea how to work this out. (I am terrible at completing squares, sorry x( )

question posted below, thanks!

Answer 1

i worked through and made it to

x^2 + 7x = 15 , but thats as far as I got (and im not sure ive even done it right so far)

Answer 2

i see what u did there
to get rid of the leading coefficient would multiply by -3 or divide ?

Answer 3

are we starting with the original problem, or the step i just put there?

Answer 4

your step looks incorrect to me
how did you get 15 ??

Answer 5

ello :D

Answer 6

-3x^2 + 7x = -5
-3x^2 + 7x +5 =0
x^2 + 7x -15 = 0
x^2 +7x =15

thats how I got there >.<

Answer 7

i'm sorry but i'm not understanding the 3rd line
-3x^2+7x+5=0 it's correct
then what action did you take to get x^2+7x-15= ????
i think i'm not familiar wit this

Answer 8

okay so we must complete the square, so;

-3x^2+7x=-5

take half of b and square it

@Bookworm14

Answer 9

@Nnesha I multiplied the 5 * -3 (commonly used in slide/divide method you multiply a*c and then divide the whole problem by -3 later)

@atreyu6s3x6 but have of 7 is 3.5 ??

Answer 10

first we have to divide by -3 both sides then we would take half of x term \[\frac{ -3x^2 }{ -3 }+\frac{7x}{-3}=\frac{-5}{-3}\]

Answer 11

oh yes! haha i forgot that step @Nnesha

Answer 12

so it becomes \[x^2 -\frac{ 7x }{ 3 } = \frac{ 5 }{ 3 }\]

Answer 13

I made the 5/3 positive because I thought the negatives signs would cancel each other out

Answer 14

that's correct you can change it into decimal

and now we need to take of half of x term to make it perfect trinomial
and then add (b/2)^2 both sides

Answer 15

\[\large\rm x^2+2.3x+\color{Red}{(\frac{2.33}{2})^2 }= \frac{5}{3} +\color{Red}{(\frac{2.33}{2})^2}\]
i changed 7/3= into 2.33 decimal

Answer 16

and remember factor of that trinomal would always be \[\rm (x+\frac{b}{2})^2\]
(x+ half of b term)^2

Answer 17

so would that become x+2.3x+1.32 = 2.98 ? (that is the simplified version of yours)

Answer 18

hmm for somehow i didn't get 2.98 at left side

Answer 19

I did it again and got 3.02 is taht what you got?

Answer 20

ye that' what i got

Answer 21

we can factor trinomal \[\large\rm\color{ReD}{ x^2+2.3x+1.32}= 3.02\]
remember when we complete the square factor of this trinomial would always be \[(x+\frac{b}{2})^2 = 3.02\]

Answer 22

answer are in fraction form
do you have calculator to convert 3.02 into fraction ?

Answer 23

make sense ?