Y=x^2-4x+8 and 4x+y=12 so y=12-4x, insert y in the quadratic to get
12-4x=x^2-4x+8
12=x^2+8
0=x^2-4=(x-2)(x+2)
So the solutions are x=2 and x=-2.
There is a difference of 3 on the x axis
The price of the bushel is 1.22, 1.41, 1.38, and 1.27.
To calculate the weighted average, all you need to is to just add all the values given above and then divide it by 4, since we only have 4 values of the bushel.
So: 1.22 + 1.41 + 1.38 + 1.27 = 5.28
5.28 / 4 = 1.32
Round it off to only two significant figures, you would get: $1.30.
He used the commutative property of addition.<span />
8.5 is the nearest one
square root of 72 is about 8.48
rounding to the nearest tenth gives you 8.5
