Combine like terms to create a equivalent expression to
2r+1+(-4r)+7

-2r+8

Step-by-step explanation:

Add 1 and 7 to get    2r+8+(-4r)

Then subtract 4r from 2r because adding a negative is the same as subtracting. so that makes your answer      -2r+8  

1 number

if we use a graphing calculator, there is only one such number that satisfies the conclusion of the mean value theorem, that is, a number such that

where the right-hand side is the average rate of change of f on the interval [0.5,0.75], which is the slope of the secant line.

in the attached graph, the black line is the secant line which has its slope as the average rate of change of f on [0.5,0.75], while the orange line is the only tangent line to the graph of f in the interval that satisfies the mvt conclusion.