Please solve the circle

In Problems 79-90, find the difference quotient of f; that is, find f (x + h ) - f(x ) 79. f(x ) = 4x + 3 -, h + 0, for each function. Be sure to simplify. 80 f(x) = -3x + 1 h 2008 + 220 81 f (x ) = x2 - 4 82. f (x ) = 3x2 + 2 83. f(x) = x2 - x+ 4 ()84. f(x) = 3x2 - 2x + 6 85. f ( x ) = - 1 87. f(x) = 2x the borboud at 86. f(x) = 88. f(x) = - 5x x + 3 x +3 ver adl meril beoqque aide x - 4 89. f (x ) = Vx - 2 90. f(x) = Vx+ 1 [Hint: Rationalize the numerator.]