5. Funkcije više varijabli, 2. dio - Rješenja 1 x + y dx − x y (x + y) dy ...
5. Funkcije više varijabli, 2. dio - Rješenja 1 x + y dx − x y (x + y) dy ... 5. Funkcije više varijabli, 2. dio - Rješenja 1 x + y dx − x y (x + y) dy ...
5. Funkcije više varijabli, 2. dio - Rješenja 1. (a) dz = (2x + y) dx + (x − 2y) dy (b) dz = 1 dx − x + y x y (x + y) dy 2. (a) d 2 z = − 1 (x+y) 2 (dx + dy) 2 (b) d2z = − 1 xdx2 + 2 y x 2 dxdy − y2dy 3. (a) dz dt = et (t ln t − 1) t ln 2 t (b) dz dt = esin t−2t3 cos t − 6t 2 (c) dz dt = (d) dz dt = 4. (a) ∂z ∂u ∂z ∂v (b) ∂z 3 − 12t2 1 − (3t − 4t3 ) 2 3 − 4 t 3 − 1 2 √ t cos 2 3t + 2 t 2 − √ t 2u = ln (3u − 2v) + v2 = −2u2 ln (3u − 2v) − v3 3u2 v2 (3u − 2v) 2u 2 v 2 (3u − 2v) ln u 2 − v 2 ∂u = 2ueuv u 2 − v 2euv−1 uv +ve u 2 − v 2euv ∂z ∂v = −2veuv u 2 − v 2euv−1 uv +ue u 2 − v 2euv ln u 2 − v 2 (c) ∂z ∂u = 2u cos u2− 2uv2 1 + v4 (v2 + u2v4 + u2 ) 2,∂z ∂v = 2u2v 1 − v4 (v2 + u2v4 + u2 ) 2 (d) ∂z ∂u = 0,∂z ∂v = 1 5. (a) y ′ = y x , y′′ = 0 (b) y ′ = − x y , y′′ = − x2 + y2 y3 6. (a) ∂z ∂x = −c2 x a2 ∂z , z ∂y = −c2 y b2z 1
- Page 2: (b) ∂z ∂x = z ∂z , x (z − 1
<strong>5.</strong> <strong>Funkcije</strong> <strong>više</strong> <strong>varijabli</strong>, <strong>2.</strong> <strong>dio</strong> - <strong>Rješenja</strong><br />
1. (a) dz = (2x + y) <strong>dx</strong> + (x <strong>−</strong> 2y) <strong>dy</strong><br />
(b) dz = 1<br />
<strong>dx</strong> <strong>−</strong><br />
x + y<br />
x<br />
y (x + y) <strong>dy</strong><br />
<strong>2.</strong> (a) d 2 z = <strong>−</strong> 1<br />
(x+y) 2 (<strong>dx</strong> + <strong>dy</strong>) 2<br />
(b) d2z = <strong>−</strong> 1<br />
x<strong>dx</strong>2 + 2<br />
y<br />
x 2<br />
<strong>dx</strong><strong>dy</strong> <strong>−</strong> y2<strong>dy</strong> 3. (a) dz<br />
dt = et (t ln t <strong>−</strong> 1)<br />
t ln 2 t<br />
(b) dz<br />
dt = esin t<strong>−</strong>2t3 cos t <strong>−</strong> 6t 2 <br />
(c) dz<br />
dt =<br />
(d) dz<br />
dt =<br />
4. (a) ∂z<br />
∂u<br />
∂z<br />
∂v<br />
(b) ∂z<br />
3 <strong>−</strong> 12t2 <br />
1 <strong>−</strong> (3t <strong>−</strong> 4t3 ) 2<br />
3 <strong>−</strong> 4<br />
t 3 <strong>−</strong> 1<br />
2 √ t<br />
cos 2 3t + 2<br />
t 2 <strong>−</strong> √ t <br />
2u<br />
= ln (3u <strong>−</strong> 2v) +<br />
v2 = <strong>−</strong>2u2 ln (3u <strong>−</strong> 2v) <strong>−</strong><br />
v3 3u2 v2 (3u <strong>−</strong> 2v)<br />
2u 2<br />
v 2 (3u <strong>−</strong> 2v)<br />
ln u 2 <strong>−</strong> v 2<br />
∂u = 2ueuv u 2 <strong>−</strong> v 2euv<strong>−</strong>1 uv<br />
+ve u 2 <strong>−</strong> v 2euv ∂z<br />
∂v = <strong>−</strong>2veuv u 2 <strong>−</strong> v 2euv<strong>−</strong>1 uv<br />
+ue u 2 <strong>−</strong> v 2euv ln u 2 <strong>−</strong> v 2<br />
(c) ∂z<br />
∂u = 2u cos u2<strong>−</strong> 2uv2 1 + v4 (v2 + u2v4 + u2 ) 2,∂z ∂v = 2u2v 1 <strong>−</strong> v4 (v2 + u2v4 + u2 ) 2<br />
(d) ∂z<br />
∂u<br />
= 0,∂z<br />
∂v<br />
= 1<br />
<strong>5.</strong> (a) y ′ = y<br />
x , y′′ = 0<br />
(b) y ′ = <strong>−</strong> x<br />
y , y′′ = <strong>−</strong> x2 + y2 y3 6. (a) ∂z<br />
∂x = <strong>−</strong>c2 x<br />
a2 ∂z<br />
,<br />
z ∂y = <strong>−</strong>c2 y<br />
b2z 1
(b) ∂z<br />
∂x =<br />
z ∂z<br />
,<br />
x (z <strong>−</strong> 1) ∂y =<br />
z<br />
y (z <strong>−</strong> 1)<br />
7. (a) dz = <strong>−</strong> 1<br />
(<strong>dx</strong> + <strong>dy</strong>)<br />
z<br />
(yz <strong>−</strong> 1) <strong>dx</strong> + (xz <strong>−</strong> 1) <strong>dy</strong><br />
(b) dz =<br />
1 <strong>−</strong> xy<br />
8. Rt . . . 2x<strong>−</strong>4y<strong>−</strong>z<strong>−</strong>5 = 0, n . . .<br />
x <strong>−</strong> 1<br />
2<br />
= y + 2<br />
<strong>−</strong>4<br />
= z <strong>−</strong> 5<br />
<strong>−</strong>1<br />
x <strong>−</strong> 1 y <strong>−</strong> 1<br />
9. Rt . . . 2x<strong>−</strong>2y+4z<strong>−</strong>π = 0, n . . . =<br />
1 <strong>−</strong>1<br />
10. U tim točkama imaju istu tangencijalnu ravninu.<br />
2<br />
= z <strong>−</strong> π<br />
4<br />
2