Question

The area of a rectangular garden is given by the trinomial x2 + 6x – 27. What are the possible dimensions of the rectangle? Use factoring.


A. x – 9 and x + 3
B. x + 9 and x – 3
C. x – 9 and x – 3
D. x + 9 and x + 3

Answer 1

If you factor, you get (x+a)(x+b), where a+b=6 (coefficient of x), and ab=-27 (constant term.
Try it now..

Answer 2

i think its A?

Answer 3

-9+3=-6

Answer 4

so its not a?

Answer 5

Nope. Try again? a+b=6 ab=-27

Answer 6

x + 9 and x + 3?

Answer 7

9+3=12 instead of -6,
9*3=27 instead of 27

Answer 8

I would take -3 and 9, so (x-3)(x+9), which would be B.
Check: -3+9=6 OK
-3*9=-27 OK

See? That's all!

Answer 9

i am confusedd

Answer 10

r u sayying its x + 9 and x – 3

Answer 11

You don't have to be, because it is entirely clear: you are looking for two numbers, a and b, to write your trinomial as (x+a)(x+b)

If you would expand (x+a)(x+b), you would get (after tidying up):

x²+(a+b)x+ab. Now you have:
x²+ 6x -27

That is why I say: a+b=6 and a*b=-27

If you think a while about this, you'll come up with a=-3 and b=9.

Answer 12

So, because x²+6x-27=(x-3)(x+9)
and area=length*width, the dimensions can only be x-3 and x+9

Answer 13

okay!!! haha i get itt. thank you.

Answer 14

YW!