Question

Solve -4√x+2 + 3 = -9

a. x=-1
b. x= 7
c. x= 31
d. x= 46

I thought 7... but that doesn't seem to work

Answer 1

take \[\sqrt{x}=p\]
So, equation stands as,
-4p+2+3=-9
4p=14
p=3.5
Hence
\[\sqrt{x}=3.5\]
Squaring we get x=3.5*3.5
So, x=12.25 which is not among the answers
Will there be an x after 2?

Answer 2

no, i dont think so..
i don't get where you got the 14 from though.

Answer 3

nevermind, it's the 2+3+9 .

Answer 4

See i had gotten the 12.25 as well, but seeing as that is not one of the answers, i dont get it.

Answer 5

hmm..this is pretty confusing..:)

Answer 6

hmm, i can't figure it out /:

Answer 7

Lets plug in each of the values
a. definitely not it as it gives a complex root
b. plugging x=7 gives a value of -5.5 instead of 9. Cross it out too.
c. LHS will give a way negative value instead of 9. Wrong too
d. Same fate as c. Cross it out too.

We should recheck the question itself shouldn't we?

Answer 8

I mean, that's all it gives me. exactly that. So , is there any other way of solving this?

Answer 9

Hmm..No idea...Am sorry..cannot help..will try and figure out something else..nothing coming to my mind now..

Answer 10

I think the question is different: \(-4\sqrt{x+2}+3=-9\).

Then \(-4\sqrt{x+2}=-12\), so \(\sqrt{x+2}=3\).

Not there are only two steps left to get your answer!

Answer 11

@brazukinhaa: seems like your original thought was not so bad...

Answer 12

@ZeHanz ....You are right..:)

Answer 13

Typing -4√(x+2) + 3 = -9 would have made it much clearer. It is because in a book or on a webpage these numbers are nicely typesetted like \(-4\sqrt{x+2}+3=-9\), but people tend to forget to type brackets if they don't use the equation editor or LATEX commands.

Answer 14

Sorry i had gone out. Okay, so i'm still not understanding which of the numbers would be the answer. but i see what you're saying. I couldn't write it like that however, i couldn't find a radical that would remain over the x+2 @ZeHanz

Answer 15

OK, we've come to:

\(-4\sqrt{x+2}+3=-9\), so
\(-4\sqrt{x+2}=-12\) (subtracted 3 from both sides)
\(\sqrt{x+2}=3\) (divided both sides by -4)

Now, don't pay attention to the number x+2 yet. Just ask yourself: the square root of what number is 3? Well, 9 of course! So the number under the radical must be 9:

\(x+2=9\) and this means that \(x=7\).

Answer 16

Yeah, that's what i had originally though, because 7+2 = 9 and then the square root being 3.
I think i get it now. Thanks so muchh! (:

Answer 17

YW!