Question

Will Medal!!!
Please help
Suppose f(x) = 3x+1 and g(x) = x^2 +2x.
Find x such that f(g(x)) = 10.

Answer 1

@ganeshie8

Answer 2

Use Wolfram alpha for this

Answer 3

wolfram alpha is not correct

Answer 4

replace each x value in f(x) with the entire function g(x)

Answer 5

f(x) = 3x+1

f(g(x)) = 3*g(x) + 1

Answer 6

What do you mean by that?

Answer 7

g(x) = x^2+2x


f(g(x)) = 3*g(x) + 1
= 3 * (x^2 + 2x) + 1

Answer 8

see that

Answer 9

yeah i get it

Answer 10

then they tell you that equals to a value and find x

Answer 11

it equals 3x^2 + 6x + 1 right

Answer 12

10 = 3x^2 + 6x + 1

Answer 13

yeah the f(g(x)) does, then they tell you that is equal to 10

Answer 14

then how do you solve it after that, that s the part which is the most confusing for me

Answer 15

it is a quadratic, to get the solution, you put it in standard form first..
ax^2+bx+c=0

Answer 16

3x^2 + 6x - 9 = 0

3*( x^2 + 2x - 3) = 0

Answer 17

then what to do next

Answer 18

so,

x^2 + 2x -3 = 0

you can always just apply the quadratic formula, but this one looks to factor easy

Answer 19

(x - 1)*(x+3) = 0

Answer 20

wait from where did x-1 come from

Answer 21

so, that is true if..

x - 1 = 0
OR
x + 3 = 0

Answer 22

x = 1 or x=-3

Answer 23

factoring a quadratic

Answer 24

ohh thanks

Answer 25

distribute the thing and check , it goes back to the original

Answer 26

or simply just plug in the coefficients to the quadratic equation and hit a button to solve for you

Answer 27

i did not get the part after this
3x^2 + 6x - 9 = 0

3*( x^2 + 2x - 3) = 0

Answer 28

what did you do after this

Answer 29

divide both sides with a 3

Answer 30

0/3 = 0

Answer 31

Once you get down to standard form

ax^2 + bx + c = 0

solving that expression for x will give you the quadratic formula

Answer 32

yeah i get it, thanxs

Answer 33

\[x = \frac{ -b \pm \sqrt{b^2 - 4*a*c} }{ 2a }\]

Answer 34

k, welcome

Answer 35

thnxs