See attached for a sketch of some of the cross sections.
Each cross section has area equal to the square of the side length, which in turn is the vertical distance between the curve y = √(x + 1) and the x-axis (i.e. the distance between them that is parallel to the y-axis). This distance will be √(x + 1).
If the thickness of each cross section is ∆x, then the volume of each cross section is
∆V = (√(x + 1))² ∆x = (x + 1) ∆x
As we let ∆x approach 0 and take infinitely many such cross sections, the total volume of the solid is given by the definite integral,

Answer:
C.y = 3x + 4
Step-by-step explanation:
We have two points, so we can find the slope
m = (y2-y1)/ (x2-x1)
= (7--2)/ (1--2)
= (7+2)/(1+2)
= 9/3
=3
The slope is 3
We can find the point slope form of the line
y-y1 = m(x-x1)
y-7 = 3(x-1)
Distribute
y-7 =3x-3
Add 7 to each side
y-7+7 = 3x-3+7
y = 3x+4
This is in slope intercept form (y=mx+b)