Determine whether the following sets form subspaces of R^3: (a) {(x1,x2,x3)^T |x1+x3=1}

(b) {(x1,x2,x3)^T |x1=x2=x3}

Determine whether the following statements are true and give an explanation or counterexample. bold a. when using the shell method, the axis of the cylindrical shells is parallel to the axis of revolution. bold b. if a region is revolved about the y-axis, then the shell method must be used. bold c. if a region is revolved about the x-axis, then in principle it is possible to use the disk/washer method and integrate with respect to x or the shell method and integrate with respect to y.

The perimeter of a triangle is 69 cm. the first is 5 cm shorter than the second side. the third side is twice as long the first side. find the length of each side

Find the distance between (0,5) & (-4,2)