Question

The gradient of the curve is given by the equation and a point on the curve is also given. Find the equation of the curve with working​

Answer 1

Answer:

4 x^(3/2)         + 5x -32

Step-by-step explanation:

This problem involves definite integration (anti-derivatives).

If dy/dx = 6x^(1/2) - 5, then dy = 6x^(1/2)dx - 5dx.

                                        (1/2) + 1

This integrates to y = 6x                        

                                   ----------------                      

                                      (1/2) + 1             x^(3/2)

                                                      =  6 ------------ + C

                                                                 3/2

             

or:        4 x^(3/2) + C

and the ∫5dx term integrates to 5x + C.

The overall integral is:  

4 x^(3/2) + C + 5x + C. better expressed with just one C:

4 x^(3/2)         + 5x + C

We are told that the curve represented by  this function goes thru (4, 20).

This means that when x = 4, y = 20, and this info enables us to find the value of the constant of integration C:

20 = 4 · 4^(3/2)         + 5·4 + C, or:

20  =  4  (8)           + 20 + C

Then 0 = 32 + C, and so C = -32.

The equation of the curve is thus   4 x^(3/2)         + 5x -32

                   

           

                                      (1/2 + 1)