amazingxin777

10 digit numbers go something like this: _ _ _ _ _ _ _ _ _ _ 

If number 2 is in the first place, it's kind of set so you basically only need to find 9 digit numbers now: _ _ _ _ _ _ _ _ _

If repition is not allowed, the first digit has 9 (no 0) choices the second also has 9 (because any number except the first chosen) the third has 8, and so on. That's basically going to be 9*9! (without the 1 but anything times 1 does nothing)

Try figuring that out!

I agree.

the point is probably to help you solve it, so if you can dof it another way, that would work as well as long as you get the right answer

but this is the addition method:

1st: Line up the variables in both equation, x above x, y above y, = above =, constant above constant. 2nd: (Optional) Multiply one or both equations so the coefficients of one variable are opposites. 3rd: Add the equations to eliminate one variable. 4th: Solve.

What pattern shown????

\(x^3+8=x^3+2^3\)

The formula for the sum of cubes is \(a^3+b^3= (a + b)(a^2 – ab + b^2)\). You should be able to do the rest within a few minutes.

My favorites! So we know that in a fraction, the denominator can never be 0. So x^2+2x+3 can not be equal to 0 and range is basically what numbers can be the output. Hopefully, that gets you started.