Wykaż, że jeśli x²+y²=2 i x+y=1 to xy= - ½
Z: x² + y² = 2 ∧ x + y = 1
T: xy = -0,5
D:
x² + y² = 2
(x+y)² = x² + 2xy + y²
(x+y)² - 2xy = 2
1² - 2xy = 2
-2xy = -1
xy = -0,5
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Litterarum radices amarae sunt, fructus iucundiores
Pozdrawiam :)
Jeżeli x²+y²=2 i x+y=1, to
(x+y)²-2xy=2, ponieważ x+y=1, więc
1-2xy=2
-2xy=2-1
-2xy=1/:-2
xy=-1/2 c.n.d.
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Z: x² + y² = 2 ∧ x + y = 1
T: xy = -0,5
D:
x² + y² = 2
(x+y)² = x² + 2xy + y²
(x+y)² - 2xy = 2
1² - 2xy = 2
-2xy = -1
xy = -0,5
----------------------------------------------------------------------------------------------------
Litterarum radices amarae sunt, fructus iucundiores
Pozdrawiam :)
Jeżeli x²+y²=2 i x+y=1, to
(x+y)²-2xy=2, ponieważ x+y=1, więc
1-2xy=2
-2xy=2-1
-2xy=1/:-2
xy=-1/2 c.n.d.