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# Whats the average rate of change of change for

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Whats the average rate of change of change for

f(x)=x^2+2x-1 as x goes from 1 to 2? Then how do i find the equation to the secant line of f(x)?

Oct 22, 2019

#1
+8652
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Whats the average rate of change of change for

f(x)=x^2+2x-1 as x goes from 1 to 2? Then how do i find the equation to the secant line of f(x)?

Was ist die durchschnittliche Änderungsrate für
f (x) = x ^ 2 + 2x-1, wenn x von 1 nach 2 geht? Wie finde ich dann die Gleichung zur Sekantenlinie von f (x)?

$$f(x)=x^2+2x-1$$

$$y_1=1^2+2\cdot1-1=2\\ P_1(1,2)$$

$$y_2=2^2+2\cdot 2-1=7\\ P_2(2,7)$$

The average rate of change is

$$m_{1,2}=\frac{y_2-y_1}{x_2-x_1}=\frac{7-2}{2-1}=\color{blue}2.5$$

The equation to the secant line of f(x) is

$$f(x)=y=m(x-x_1)+y_1$$

$$F(x)=y=2.5(x-1)+2=2.5x-2.5+2$$

$$f(x)=y=2.5x-0.5$$

!

Oct 22, 2019
#2
+655
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Amazing explanation asinus!!

Nirvana  Oct 23, 2019