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Please explainthanks

 Nov 25, 2018
edited by YEEEEEET  Nov 25, 2018
edited by YEEEEEET  Nov 25, 2018
 #1
avatar+107348 
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y(x) = x(x + 3)   =  x^2 + 3x

 

(a)  We have this difference quotient 

 

[ (x + h)^2 + 3(x +h) - (  x^2 + 3x) ]

_________________________               simplify

            h

 

[  (x^2 + 2xh + h^2 +  3x + 3h)   - (x^2 + 3x) ]

___________________________________

                   h

 

[ 2xh + h^2 + 3h - ]

________________

           h

 

h [ 2x + h + 3 ]

____________

        h

 

 

2x + h + 3          and when h → 0, we have

 

2x + 3    ...... this is the gradient at any x  value on the curve

 

(b)   The gradient  of the curve at (-5, 10) is

 

2(-5) + 3   =      -7

 

 

cool cool cool

 Nov 26, 2018
edited by CPhill  Nov 26, 2018

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