interesting word prob: A negative number is 12 less than...

[ultrasonicsite]

I can't seem to grasp the concept.

"A negative number is 12 less than its square. Find the number."

OK!!! Let me put this into an equation.

A negative number, "-x", is equal to twelve less than its square, or x^2 - 12. So basically:

. . .x^2 - 12 = -x

Is that okay so far? So em, everything after this is probably wrong.

Let's see... Add 12 to both sides? Nooo wait. Subtract.

-actually no, I am completely lost.

I tried to imput some random numbers in to see what happens:

. . .Assume x=-2

. . .-2=-(2^2)-12
. . .-2=-4-12
. . .-2=-16

That statement is completely false.

 

[skeeter]

"A negative number is 12 less than its square. Find the number."

let x = the number (notice that I didn't put a negative sign in front of it)

x = x² - 12

0 = x² - x - 12

0 = (x - 4)(x + 3)

x = 4, x = -3

you wanted the negative solution ... the number x = -3.

the square of -3 is 9 ... -3 is 12 less than 9, isn't it?

 

[ultrasonicsite]

Thanks a lot for the help!

 

[Denis]

Re: interesting word prob: A negative number is 12 less than

. . .x^2 - 12 = -x
Let's see... Add 12 to both sides? Nooo wait. Subtract.
-actually no, I am completely lost.

Add x to both sides:
x^2 + x - 12 = 0

If you can't solve that for x, you need to see your teacher...