Question

if a+b=3 and a^2+b^2=7, then what is the value of a^4 +b^4?

Answer 1

can you find ab first ?
from a+b and a^2+b^2 ?

Answer 2

because, you'll need a^2b^2

Answer 3

1+2=3?

Answer 4

For the first part

Answer 5

1+2 ?
you guessing nu,bers ?

Answer 6

Yes

Answer 7

use this :
\((a+b)^2 = a^2+b^2+2ab\)
to find the value of ab

can u?

Answer 8

no quite

Answer 9

you know values of a+b and a^2+b^2
just plug those in that formula...

Answer 10

\((a+b)^2 = a^2+b^2+2ab\)
(3)^2 = 7+2ab

Answer 11

now ?

Answer 12

Yes, thanks

Answer 13

3/2=ab

Answer 14

good,
so once you have ab,
use this
(a^2+ b^2) ^2 = (a^4+ b^4) + 2 a^2b^2

you know a^2+b^2 , a^2b^2 , and you need a^4+b^4

Answer 15

and ab is NOT 3/2
try again ?

Answer 16

ab=1?

Answer 17

yup, ab =1 is correct :)

Answer 18

-1=a^4+b^4

Answer 19

lets check
(a^2+ b^2) ^2 = (a^4+ b^4) + 2 a^2b^2
7^2 = (....) + 2 (1)

how you got -1 ? :O

Answer 20

I got confused (a^2... with a+b

Answer 21

47=a^4+b^4

Answer 22

i get 47 too :)

Answer 23

Thanks so much! You are awesome:)

Answer 24

your welcome ^_^
you are a good learner too.