Question

{2xy+5(x+y)=55
{6xy+3(x+y)=81
{x+y=S
{x•y=P
Va rog ajutor

Answer 1

{2xy+5(x+y) = 55
{6xy+3(x+y) = 81

{x+y = S
{x×y = P

{2P+5S = 55
{6P+3S = 81 /:3

{2P+5S = 55
{2P+S = 27 /•(-1)

{2P+5S= 55
]-2P-S = -27

2P cu -2P se reduc:

4S = 28
S = 28/4
S = 7.

2P+S = 27
2P+7 = 27
2P = 27-7
2P = 20
P = 20/2
P = 10.

{S1 = 7
{P1 = 10

{S2 = 10
{P2 = 7

S = {(7;10);(10;7)}





J'espère aidé :)

Answer 2

2P+5S=55
6P+3S=81

-6P-15S= - 165
6P+3S=81
(+)

-15S+3S=-165+81
-12S=-84
S=-84:(-12)
S=7

6P=81-3*7
6P=81-21
6P=60
P=10

X+Y=7
XY=10

X=7-Y
(7-Y)Y=10
7Y-Y^2 -10=0
delta=49-4*(-1)*(-10=49-40=9
Y1=(-7+3):(-2)=2
Y2=-10:(-2)=5

PT Y1=2 => X1=7-2=5
PT Y2=5 => X2=7-5=2