2006-10-14 22:12:58 · 14 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
easy
(x+y)^2 = x^2 +y^2 + 2xy
(x-y)^2 = x^2 + y^2 - 2xy
add the 2
(x+y)^2 + (x-y)^2 = 2x^2 + 2y^2 = 2(x^2+y^2)
put the values on left from the question
8^2 + 2^2 = 2(x^2+y^2) or 2(x^2+y^2) = 64+ 4 = 68
2006-10-14 22:15:20 · answer #1 · answered by Mein Hoon Na 7 · 0⤊ 0⤋
x + y = 8
x - y = 2
2x = 10
x = 5
y = 3
Now, 2x^2 + 2y^2 = 2*5*5 + 2*3*3 = 50+18 = 68
2006-10-14 22:51:41 · answer #2 · answered by Anonymous · 0⤊ 0⤋
This is simple.
(1) x + y = 8
(2) x - y = 2
I'm first going to find the value of each variable to simplify things.
Adding (1) to (2),
(x + y) + (x - y) = 10
2x = 10
x = 5
Substituting x = 5 into (1),
x + y = 8
y + 5 = 8
y = 3
To find the value of 2x^2 + 2y^2, just substitute the values of x and y into the equation. Having already finding out that x = 5 and y = 3,
2x^2 + 2y^2
= 2(5)^2 + 2(3)^2
= 2(25) + 2(9)
= 50 + 18
= 68
Hope this helps.
2006-10-15 02:10:48 · answer #3 · answered by xxmizuraxx 2 · 0⤊ 0⤋
x+y=8 .... (1)
x-y=2 ...... (2)
from x-y=2, you derive that x=2+y .... (3)
Substitute that in (1) you get 2+y+y=8
2y=8-2; y=6/2, y=3
Substitute this value for y in (3), x=2+3, x=5
Substitute the values x=5 and y=3 in 2x^2+2y^2
2(5^2)+2(3^2) = 50 + 18 = 68
2006-10-14 22:23:38 · answer #4 · answered by Loral 2 · 0⤊ 0⤋
x+y=8 is the same as x=8-y
x-y=2 is the same as x=2+y which means 8-y=2+y so 2y=6
y=3
x+3=8 so x=5
2(3^2)+2(5^2) = 2(9)+2(25) = 18+50= 58
58 is the answer!
2006-10-14 22:58:28 · answer #5 · answered by speed25247 1 · 0⤊ 0⤋
Sum two equations: 2x=10 then x=5
choose one of the equations,replace X, we have: 5+y=8 then y=3
2x^2+2y^2=2(5)^2+2(3)^2=68
2006-10-14 22:54:08 · answer #6 · answered by Alex 4 · 0⤊ 0⤋
x+y=8........(1)
x-y =2........(2)
add (1) and (2)
>>>>> 2x=10 >>>>> x=5
substitute x in (2)
5-y=2 >>>>>>>> y=3
2x^2+2y^2 = 2*5^2+2*3^2=2*25+2*9
=50+18=68
i hope that this helps
2006-10-14 23:30:01 · answer #7 · answered by Anonymous · 0⤊ 0⤋
To multiply out (x + 5)(2x^2 + 4x + 2)... start up by way of multiplying x by way of each and every thing in the 2d set of parentheses: 2x^3 + 4x^2 + 2x Now, do the comparable element with 5 (and line the words up this form!): .........10x^2 + 20x + 2 upload the two strains at the same time and you get: 2x^3 + 14x^2 + 22x + 2 this could simplify to: 2(x^3 + 7x^2 + 11x + a million)
2016-12-08 15:03:04 · answer #8 · answered by Anonymous · 0⤊ 0⤋
x+y=8 and x-y=2
add these two
x+y=8
x-y=2
-----------
2x=10
therefore x=5 and put this value of x in x+y=8 orx-y=2
if we put x=5 in x+y=8 we get
5+y=8
therefore y=3
so we have x=5 and y=3
2x^2+2y^2=2(5)^2+2(3)^2
=2(25)+2(9)
=50+18
=68
2006-10-14 22:52:02 · answer #9 · answered by manjit k 1 · 0⤊ 0⤋
2x = 10
x = 5
y = 3
50 + 18 = 68
2006-10-14 22:53:27 · answer #10 · answered by Helmut 7 · 0⤊ 0⤋