Prove: if a+c=b+c, then a=b.
statement 1: a+c=b+c
statement 2: a+c+(-c)=b+c+(-c)
statement 3: a+[c+(-c)]=b+[c(-c)]
statement 4: a+0=b+0
statement 5: a=b.
what is the reason for statement 2?
a. property of opposites
b. associative property of addition
c. addition property of equality
d. identify property of addition

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

Which of the following circles have their centers on the x-axis? check all that apply.

For every corresponding pair of cross sections, the area of the cross section of a sphere with radius r is equal to the area of the cross section of a cylinder with radius and height 2r minus the volume of two cones, each with a radius and height of r. a cross section of the sphere is and a cross section of the cylinder minus the cones, taken parallel to the base of cylinder, is the volume of the cylinder with radius r and height 2r is and the volume of each cone with radius r and height r is 1/3 pie r^3. so the volume of the cylinder minus the two cones is therefore, the volume of the cylinder is 4/3pie r^3 by cavalieri's principle. (fill in options are: r/2- r- 2r- an annulus- a circle -1/3pier^3- 2/3pier^3- 4/3pier^3- 5/3pier^3- 2pier^3- 4pier^3)