ElectricPavlov

There ya go......

That is what I simplified the expression to also (see above)     the SUM of the SQUARES of the coefficients is given in my answer above......what part do you not understand?  

  -7^2 +4^2 + 13^2   + 1^2      

    (some will argue '1' is not a coefficient....but it could be the coefficient of  x^o  ...depends on what you have been taught ...is the '1' a coefficient in your teachings or is it considered a 'constant' ?   )

4 x^2 -8x+8       - 7x^3 + 21x - 7      collect like terms

-7 x^3 + 4x^2 + 13x + 1              -7^2 +4^2 + 13^2   + 1^2      

    (some will argue '1' is not a coefficient....but it could be the coefficient of  x^o  ...depends on what you have been taught )

The only people out of the  30

      that visited ONLY one place are the     7      and the   10   in the circles = 17   out of total 30  

                17/30

a +      a +d     + a + 2d = 24

3a + 3d = 24

a + d = 8        d = 8-a                    

a (a+d)(a+2d) = 440

a (8)(a + 2d) =440

8a^2 +16ad = 440

8a^2 + 16(a)(8-a)

8a^2 + 128a -16a^2 -440 = 0

-8a^2 +128a-440 = 0                          Quadratic Formula    a = 5 or 11

results in     5    8    11   

Look at this:

There is only one number in the intersection....     

     ONE number out of   .........   total numbers 

Fully expand the two equations and equate them  (first one is    x^2-4x+4+y^2-6y+9 - 9 = 0  ) and you will find it boils down to this

4-6y = 4 + 8y

14y = 0

y = 0       then sub this into either one of the equations  to find the value of x = 2

One point  of intersection:   2,0   

1/30   + 1/90   = 1/x    solve for 'x' the amount of time required for both working together

3 / 90  + 1/90  = 1/x

4/90 = 1/x

90/4 = 22.5 minutes = x

c+r =10

d+r=20

d+c=24

d+c+r = ?  

Add the first three equations together to get

2c + 2r + 2d = 54     now divide by 2

c+r+d = 27 kg

First, find the equation of the dashed line :  y =  1/2  x-1/2

    the shaded area is GREATER than this line, but does not include the line

y > 1/2 x - 1/2