Question

If a number is decreased by its square, the result is 2/9. Find the number

Answer 1

This is the same type of problem sakigirl, just write the equation out and solve it similarly:\[x-x^2=\frac{2}{9}\]

Answer 2

let x be that number
a number decreased by its square is x - x^2 = 2/9
9x - 9x^2 = 2
9x^2 - 9x + 2 = 0
(3x-2)(3x-1) = 0
equate each factor to 0 then solve for x

Answer 3

I get -1 and +2

Answer 4

remember you're looking for x. you'll get 3x = 2 and 3x = 1. You have to divide by the coefficient to get x

Answer 5

Wait, this is what I did:
x-x^2-2/9=0
I multiplied everything by nine to make it easier on me:
9x^2-9x-18
And then I factored out the 9:
9(x^2-x-2)
And then I factored from there on:
(x-2)(x+1)
which is how I get my answer: x=2, -1

Answer 6

if you multiply 2/9 by 9 you get 2. 9 just cancels out

Answer 7

not 18

Answer 8

Oh gosh, what a careless mistake.
So I guess I have to use the quadratic formula?

Answer 9

you can. but factorable too. i presented the factors,

Answer 10

but that kind of factoring is confusing so quadratic formula may be better

Answer 11

Okay thank you!