Can someone explain this differentiation question to me? i can differentiate but then i'm not sure what i am doing

note that gradient = at x = a

calculate for each pair of functions and compare gradient

(a)

= 2x and = - 1

at x = 4 : gradient = 8 and - 1 : 8 > - 1

(b)

= 2x + 3 and = - 2

at x = 2 : gradient = 7 and - 2 and 7 > - 2

(c)

= 4x + 13 and = 2

at x = - 7 : gradient = - 15 and 2 and 2 > - 15

(d)

= 6x - 5 and = 2x - 2

at x = - 1 : gradient = - 11 and - 4 and - 4 > - 11

(e)

y = √x =

= 1/(2√x) and = 2

at x = 9 : gradient = and 2 and 2 >

set each factor equal to 0

4x-3 = 0

2x-1 = 0

solve for x.

4x-3=0

4x=3

x= 3/4

solve for x. 

2x-1= 0

2x= 1

x= 1/2

your answer should be 1/2 is less than or equal to x and 3/4 is greater than or equal to x