Due to the poor economy, a real estate investor lost 120 thousand dollars in 2008. Let the ordered pair (2008, -120) represent this relationship. The

investor did better in 2010 by earning 350 thousand dollars. Let the ordered

pair (2010, 350) represent this relationship. Ruben was asked to calculate the

average rate of change for the investor's earnings from 2008 to 2010.

To solve this, Ruben uses the slope formula to calculate the rate of change

between 2008, -120) and (2010, 350). The student's work is shown below:

(a) Using complete sentences, explain the two mathematical errors in the

student's reasoning.

(b) Calculate the correct rate of change between (2008, -120) and (2010,

350)

solution:

the given function is ,

      =

the three roots of this quadratic function is , 0 ,8 and 10.all the roots are real and rational.

if a quadratic equation is of the form ,

sum of the roots = a + b +c= 0+8+10=18=  

product of roots taken two at a time = a b + b c+ c a = 0+80+0=80 =  

product of roots = a b c = 0=  

there are 11 doors in a hall starting from 0 to 11.the entry in the hall is permitted through gate number 0 and exit is allowed through only gate number 8 and 10.so, three roots(0,8,10) of quadratic function is given by entry and exit route of this hall.

hello from mrbilldoesmath!

answer:   x^2 + y^2 = 1024

discussion:

the equation of a circle with center (h,k) and radius "r" is

(x-h)^2 + (y-k)^2 = r^2.

in our case

(x-0)^2 + (y-0) ^2 = 32^2 = 1024

you,

mrb