- Sun Jun 28, 2015 4:52 pm
- Forum: Intermediate Algebra
- Topic: Two equations with two unknowns
- Replies:
**2** - Views:
**148**

Start with criss-cross multiplication.

- Mon Apr 20, 2015 1:45 pm
- Forum: Pre-Algebra
- Topic: Payment formula
- Replies:
**2** - Views:
**812**

Using 200,000 borrowed, over 25 years, rate 6% annual compounded monthly P = Payment (?) A = Amount borrowed (200000) n = number of payments (25 * 12 = 300) i = periodic (monthly) interest rate (.06/12 = .005) Formula: Let v = 1 / (1 + i)^n P = Ai / (1 - v) v = 1 / 1.005^300 = .22396.... P = 200000(...

- Tue Mar 25, 2014 10:57 am
- Forum: Advanced Algebra ("pre-calculus")
- Topic: Parabola Problem
- Replies:
**2** - Views:
**1504**

- Tue Mar 25, 2014 10:52 am
- Forum: Intermediate Algebra
- Topic: Arch Problem
- Replies:
**2** - Views:
**1004**

No graph paper?

- Mon Mar 17, 2014 5:27 am
- Forum: Advanced Algebra ("pre-calculus")
- Topic: Logarithm equation
- Replies:
**5** - Views:
**1598**

JC531 wrote:log_{5}(x-1)

Did you know that equals log(x-1) / log(5) ?

- Sun Mar 16, 2014 7:31 pm
- Forum: Geometry
- Topic: Parabola equation
- Replies:
**2** - Views:
**7341**

I didn't times it all out, but I got y = [(e-v)/(d-u)^2](x-u)^2 + v I think mine probably ends up like yours if you do all the steps. (Do you have to do all that?) Ok, but a parabola equation is of this format: y = Ax2 + Bx + C I really should have made mine clearer: y = Ax^2 + Bx + C where: A = (e...

- Sun Mar 16, 2014 4:53 am
- Forum: Geometry
- Topic: Parabola equation
- Replies:
**2** - Views:
**7341**

GIVEN:

coordinates of vertex: (u,v)

coordinates of a point on parabola: (d,e)

Find equation of parabola

I got:

y = [(e - v) / (d^2 + u^2 - 2du)]x^2 - (2au)x + au^2 + v

Can someone confirm? Thank you.

coordinates of vertex: (u,v)

coordinates of a point on parabola: (d,e)

Find equation of parabola

I got:

y = [(e - v) / (d^2 + u^2 - 2du)]x^2 - (2au)x + au^2 + v

Can someone confirm? Thank you.

Any reasons why this forum is so inactive?

I joined yesterday, and there's been no posts since.

And most "last posts" in categories are earlier than 2014.

Kind of disappointing, given all the wonderful lessons available here...

I joined yesterday, and there's been no posts since.

And most "last posts" in categories are earlier than 2014.

Kind of disappointing, given all the wonderful lessons available here...