Question

Please help me with this problem :) It is a radical equation, thanks!

Answer 1

\[x-\sqrt{10-9x}=-20\]

Answer 2

Descriptions are loved :D I have a test so i need to understand this stuff better

Answer 3

square the whole equation, you'll get
(x^2) - 10 -9x = 400
(x^2) - 9x - 410 = 0
solve the quadratic

Answer 4

How did you get x^2?

Answer 5

sasogeek not is right

Answer 6

yes you need

Answer 7

square both sides

Answer 8

that sounds right, like ( )^2 on both sides?

Answer 9

(x-sqrt(10-9x))2 = 400

Answer 10

so than we will get x2 -2xsqrt(10-9x) +(10-9x) =400

Answer 11

square every term in the equation to clear the square root sign
\[(x) ^{2} - (\sqrt{10-9x} )^{2} = (-20)^{2}\]\[x ^{2} - (10-9x) = 400\]\[x ^{2}-9x-410=0\]

Answer 12

how do you solve the bottom Saso, I have issues with x^2

Answer 13

x2-2sqrt(10-9x) +10-9x =400
-2sqrt(10-9x)=400-x2-10+9x
-2sqrt(10-9x)=390-x2+9x thsi you need squared again
4(10-9x)=(390-x2+9x)2

Answer 14

johnyy i think you're answering a whole different question...

Answer 15

sasoo how you square (a+b) this not is equal a2+2ab+b2

Answer 16

???

Answer 17

you're so wrong and i'll tell u why

Answer 18

on the left part there is a-b

Answer 19

\[x^{2}-9x=410\] Is this how it should look next Saso? How do i go about solving the rest if it is?

Answer 20

notice that, any number under a square root is the same as the number raised to the power 1/2. hence if u square it again, you'll have the powers multiplying, (1/2)2, this will result in 1. hence you'll have the number under the square root unchanged and the square root goes away

Answer 21

and yes that's how it should look like, but because it is a quadratic, you move everything to one side and solve for x

Answer 22

Starshine7 check it before you belive

Answer 23

yes but on the left parte there is a-b squared

Answer 24

what will be equal a2-2ab+b2

Answer 25

It says I should factor somewhere in this problem?? Ugh im confused

Answer 26

johnyy you're confused, relax and let me explain okay :)

Answer 27

chek it the answer in your book

Answer 28

sasogeek calcule when there is a-b squared how many will be ?

Answer 29

let me use ur theory to prove u wrong :)

Answer 30

ok let's go i will wait

Answer 31

lol maybe i should grab some popcorn XD

Answer 32

Starshine7 can you check the answer in your mathbooke

Answer 33

Its online, and it tells me that the answer is one number (example: 1,2,3)

Answer 34

(x+20)2=10-9x
x2+40x+400=10-9x
x2+49x+390=0

Answer 35

you need to solve this quadratic equation

Answer 36

when u have \[\sqrt{a}\]
it is the same as \[(a)^{1/2}\]
so if u have \[\sqrt{a-b}\]
it is the same as \[(a-b)^{1/2}\]
now if u have (a-b)
\[(a-b)^{2}=a ^{2}-2ab+b ^{2}\]
you should realize that
\[\sqrt{a-b}\neq(a-b)\]
hence the (a-b)^2 law doesn't apply
\[(\sqrt{a-b})^{2}=((a-b)^{1/2})^{2}\]
\[(1/2) \times 2 = 1\]
implying that
\[((a-b)^{1/2})^{2}=(a-b)^{1}\]\[=(a-b)\]

Answer 37

I'm really confused o.o You are solving a radical equation right? How do you solve and equation with x^2?

Answer 38

that's quite difficult to explain lol but lets see

Answer 39

do u have an idea how to do it already?

Answer 40

I'm not sure, squaring stuff just confuses me, I have memory issues so grasping stuff can be harder for me i tend to blank out

Answer 41

umm do u have skype? it'll be easier to teach that whole topic of solving quadratics on there than here, not that i can't do it here, it'll just be way easier

Answer 42

i dont, im on a mac. :) Thanks so much for your time though, I really appreciate it. its only my own fault that I dont understand it.

Answer 43

nahh don't sweat it ;) you should read more on google then

Answer 44

I may try youtube lol but they are not really that informative on certain things

Answer 45

search for khanacademy on youtube

Answer 46

sowhen you want solve one quadratic equation first calcule the discriminat what is equal b2-4ac and hence

Answer 47

do you know this methode ?

Answer 48

he mentioned he has little knowledge about quadratics... don't teach him that yet

Answer 49

i have wrote to Sunshine7

Answer 50

so than ok bye

Answer 51

Johyy what grade are u in?

Answer 52

I'm a girl O.O

Answer 53

lol its ok :P

Answer 54

haha XD

Answer 55

sorry for calling u a he then :)

Answer 56

:) thats okay