Jeremiah invested $x at a 6% simple annual interest rate account. Six times that amount was invested at an 9% simple annual interest rate account. How much was invested at the 6% account if the total annual return was $800.00?

Step-by-step explanation:

We will make a table with the values for both a 6% account and a 9% account.

The formula for this problem is Prt = I, where P is the amount invested in each account, r is the interest rate each carries in decimal form, t is the time in years, and I is the interest earned from the multiplication of the 3 previous values. We don't know how much is invested in either account, but we do know that no matter how much is invested in the 6% account, there is 6 times that in the 9% account. We know that the 6% account has a decimal rate of .06 and that the 9% account has a decimal rate of .09. "Annual" means 1 year, so the time is 1 year. Filling in the table, then:

                     P  *    r     *     t     =     I

Acct 6%         x     .06         1

Acct 9%       6x    .09          1

What we do with those number is multiply them straight across each row to get the amount of interest earned from each:

                    P     *     r     *     t     =     I

Acct 6%       x      *  .06    *    1      =   .06x

Acct 9%      6x     *  .09    *    1      =   .54x

The amount of Interest for both ADDS UP to 800; therefore:

.06x + .54x = 800 and

.6x = 800 so

x = 1333.33

That's how much was invested in the account that earned 6% interest annually.  

720

step-by-step explanation:

first i did work 2nd i did work and 3rd i did work

if the eqn of the parabola is f(x) = (x-4)(x+2), we need to mult. this out to find the coordinates of the vertex.

then f(x) = x^2 + 2x - 4x - 8, and f(x) = x^2 - 2x - 8.

one way in which you can find the vertex is to calculate x = -b / (2a).   here, that comes to

        )

x = = 1.   f(1) = 1^2 - 2(1) - 8 = - 9.   vertex is at (1, -9).

        2(1) 

find another point on the curve:   let x=0, for which y=-8.   then (0, -8) is on the curve.   plot the vertex and this point and draw a smooth parabola thru both.

hope this