Question

The square of 9 more than a number is equal to 9 more than the square of the number. What is the number?

Answer 1

n+9^2=n^2+9? @sid0830

Answer 2

No bro, it will be
\[(x+9)^2=x^2+9\]
Did you get it?

Answer 3

Omg, that's the same thing I wrote. Just different variable

Answer 4

No..I have whole square on LHS..check out yours

Answer 5

Oh, I see. Okay, now help me work it out. What's the first step.

Answer 6

kemist's equation is correct

Answer 7

i dont see square of 'sum'

Answer 8

Let the number be x
9 more than the number=x+9
Square of 9 more than the number=(x+9)^2
Square of the number=x^2
9 more than square of then number=x^2+9
Put it all together, we get

\[(x+9)^2=x^2+9\]

Answer 9

We just got that part 10 mins ago. I need to know the first step in how to solve it.

Answer 10

(x+9)^2=x^2+9
x^2+81+18x=x^2+9
18x=9-81=-72
x=-72/18=-4
Is it clear now?

Answer 11

x=-4? I got the x^2+81 part but the 18x and such I don't understand.

Answer 12

(a+b)^2 expansion formula