The base of a solid is the region enclosed by the graphs of y=x2−5x+7 and y=3, between x=1 and x=4.Cross sections of the solid perpendicular to the x-axis are rectangles whose height is x.Which one of the definite integrals gives the volume of the solid?Choose 1 answer:(A) ∫14(x2−5x+4)⋅xdx(B) π∫14(x2−5x+4)2dx(C) ∫14(x2−5x+4)2dx(D) ∫14(−x2+5x−4)⋅xdx
Q. The base of a solid is the region enclosed by the graphs of y=x2−5x+7 and y=3, between x=1 and x=4.Cross sections of the solid perpendicular to the x-axis are rectangles whose height is x.Which one of the definite integrals gives the volume of the solid?Choose 1 answer:(A) ∫14(x2−5x+4)⋅xdx(B) π∫14(x2−5x+4)2dx(C) ∫14(x2−5x+4)2dx(D) ∫14(−x2+5x−4)⋅xdx
Define Volume Integral: To find the volume of the solid, we need to integrate the area of the cross-sections along the x-axis from x=1 to x=4. The area of each rectangular cross-section is given by the difference in the y-values of the two functions (y=3 and y=x2−5x+7) times the height of the rectangle, which is x. So, the area A(x) of a cross-section at a point x is A(x)=(3−(x2−5x+7))⋅x.
Simplify Area Expression: First, simplify the expression for A(x) by distributing x and combining like terms:A(x)=(3−x2+5x−7)⋅xA(x)=(−x2+5x−4)⋅xA(x)=−x3+5x2−4x
Integrate to Find Volume: Now, we need to integrate A(x) from x=1 to x=4 to find the volume V of the solid:V=∫x=1x=4A(x)dxV=∫x=1x=4(−x3+5x2−4x)dxThis corresponds to one of the answer choices.
Match with Answer Choices: Comparing the integral we found with the answer choices, we see that it matches with choice D: Dextstyle∫x=1x=4(−x3+5x2−4x)dx
More problems from Find derivatives of using multiple formulae