Question

how do i do this math problem?

Answer 1

like ik how to do the problem but 5 mult. by 2 square root 7 gets me
i probably am making it harder then i seems :/

Answer 2

it is the form of (a+b) (a-b) = a^2 -b^2 where a = \(2\sqrt7\) and b = 5
do it again, please

Answer 3

hmm..
but i am confused on how to mult. \[2\sqrt{7} and 5\]

Answer 4

eh the middle term actually cancel you don't have to worry about them
like @Loser66 stated \((a-b)(a+b)=a^2-b^2\)
if you don't believe this foil it
you will get \((a-b)(a+b)=a^2+ab-ba-b^2=a^2+\cancel{ab}-\cancel{ab}-b^2\)

Answer 5

so same goes for your case \(a=2\sqrt{7},~~b=5\)

Answer 6

oh but how do i mult. them to solve the rest?
would it be \[10\sqrt{35}\]

Answer 7

here look at this \((2\sqrt{7}-5)(2\sqrt{7}+5)=4\sqrt{49}+10\sqrt{7}-10\sqrt{7}-5\times5\)

Answer 8

same way i did with a and b
this is always true when you see something of this sort\((a-b)(a+b)\)

Answer 9

ohhhhhhhh that makes soo much more sense now
mult. the coefficients but the coefficients !!
and yes i get the rest of how u answer the problem :)
that u for your time and patience and of course for helping me figure this out :D

Answer 10

thank*

Answer 11

i see your mistake 5 cannot go into radical
5 is a different quantity that \(\sqrt{7}\)

Answer 12

you can think of it a coefficients hehehe

Answer 13

you are welcome^_^

Answer 14

^-^

Answer 15

Hmm... I don't even know...

Answer 16

have you studied irrational numbers recently?

Answer 17

me ?

Answer 18

yeah

Answer 19

yes i did i think :P

Answer 20

this is review from algebra 2 lol

Answer 21

well, radicals are irrational numbers. they have their properties

Answer 22

yeah :)

Answer 23

let's see xD how would you do this \((1-\sqrt3)(1+\sqrt{3})=?\)

Answer 24

gimme a sec to solve that i have plenty of math hw that look like that :P

Answer 25

alright^_^

Answer 26

by the way \(1+\sqrt{3}\) is called conjugate of \(1-\sqrt{3}\)

Answer 27

would it be?
2

Answer 28

negative 2 that is
not 2

Answer 29

cause 1-\[\sqrt{9}\]
is 2 ?

Answer 30

ohhhh yes soorry that is wat i meant ;)

Answer 31

yes that's 1-3=-2

Answer 32

1-3=-2
:P

Answer 33

No worries^_^

Answer 34

hahah ;D
thx again

Answer 35

you are doing good, just practice more and more
you are welcome^_^

Answer 36

:D