Given:
Three numbers in an AP, all positive.
Sum is 21.
Sum of squares is 155.
Common difference is positive.
We do not know what x and y stand for. Will just solve for the three numbers in the AP.
Let m=middle number, then since sum=21, m=21/3=7
Let d=common difference.
Sum of squares
(7-d)^2+7^2+(7+d)^2=155
Expand left-hand side
3*7^2-2d^2=155
d^2=(155-147)/2=4
d=+2 or -2
=+2 (common difference is positive)
Therefore the three numbers of the AP are
{7-2,7,7+2}, or
{5,7,9}
Answer:
or 2 
Step-by-step explanation:
entered it into my calculator
If I am correct it should just be a cube
Step-by-step explanation:
The standard form for a line is Ax+By=C
First, we need to find the slope, or change in y over change in x. For the first one, this is
, which is impossible to find as we cannot divide by 0, meaning that this is constant horizontally -- in this case, x=2. Thus, we have 1*x+0*y=2.
For the second one, we can find the slope by getting
. We can then take the point (3,0) (it can be any point on the line) and get our equation to be y-0 = (-2/3) (x-3). Converting this to standard form, we can expand this to get
y= (-2/3)*x +2
(-2/3)*x+1*y = 2
