Question

Let f(x)=5x^2. Find a value A such that the average rate of change of f(x) from 1 to A equals 60.

Answer 1

the average rate of change is just (f(A) - f(1))/(A-1)

Answer 2

i know!

Answer 3

im getting the wrong answer for some reason though

Answer 4

and im getting frustrated

Answer 5

\[\frac{5a^2-5.1^2}{a-1}=60\]
\[5a^2-5=60(a-1)\]
\[5a^2-5=60a-60\]
\[5a^2-60a-5+60=0\]
\[5(a^2-120a+11)=0\]

Answer 6

5.1?

Answer 7

\[a=\frac{1}{2}(12\pm\sqrt{12^2-4(11)})\]

Answer 8

its easier for me to get to the . then the *

Answer 9

\[\frac{5a^2-5(1)^2}{a-1}=60=> \frac{5(a^2-1)}{a-1}=60\]
\[=>\frac{5(a-1)(a+1)}{a-1}=60 => 5(a+1)=60=> a+1=12\]

Answer 10

pfft!! thats cheating, and only gets one of them :)

Answer 11

ITS 11!!!!!!!!!!!!!!! O MY GOD!!!!!!!!!!!!!!!!!!!!!!!!

Answer 12

144-44 = 100

sqrt100 = 10

12 +- 10
/2 /2

6 +- 5 = 1 and 11?

Answer 13

cant be 1 so that leaves 11, yeah

Answer 14

a cannot be 1 dear lol

Answer 15

lol

Answer 16

i was getting to that :)

Answer 17

so my way gets all the possible values of A lol

Answer 18

not the complex ones :P

Answer 19

shhh lets not go there lol