Question

Solve: x+sqrt(x) = 20

Answer 1

\[x + \sqrt{x}\]

Answer 2

Could you show us what you've done with the question please?

Answer 3

= 20

Answer 4

i haven't done anything i don't know how to start it lol sorry

Answer 5

Well firstly, have you learnt substitution?

Answer 6

yes

Answer 7

Okay, well we should let
\[u=\sqrt{x}\]

Answer 8

So everytime you see \sqrt{x} or x(which is ideally (\sqrt{x})^2 substitute u in.

Answer 9

ok so then u^2 + u = 20

Answer 10

Yep then move the 20 to the LHS and solve the quadratic as per usual.

Answer 11

that doesn't give me the right answer

Answer 12

And the after you get the two values of "u", revert back to \sqrt{x} to find the values of x.

Answer 13

And then*

Answer 14

that gave me 4,-5 the answers are 0 and 16

Answer 15

how do i revert those back?

Answer 16

We're not done yet. You havem
t checked your answers back to the original equation.

Answer 17

Haven't*

Answer 18

Firstly.
\[u=4\]
or \[u=-5\]

Answer 19

correct then what from there

Answer 20

Then rewrite u as \sqrt{x}. So you have this:
\[\sqrt{x}=4\]
or \[\sqrt{x}=-5\]

Answer 21

Now you square everything and you can find the two values of x.

Answer 22

do you only fill it in for the sqrt root x or do you do it also for the other x that isn't sqqred

Answer 23

like what should it look like?

Answer 24

No, let's do the first one. What's x for the first one.
\[\sqrt{x}=4\]
\[x=?\]

Answer 25

i have this right now