. | -3 | .10: 67, 68, 74, 78, 83, 86, 92, 95,179, 193. |
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1 67: : y′ +2 xy = x . (1)
:
1). : y′ + P (x)∙ y = Q (x).
2). , :
a 0. : y = u ∙ v.
a 1. : : u = .
a 2. v: v = +.
a 3. : y = u ∙ v = ∙ .
3). : , : y′ + P (x)∙ y = Q (x)!
a 0. : y = u ∙ v.
a 1. : =2 = x 2 → u = .
a 2. v: v = += + = = +;
a 3. : y = u ∙ v = ∙ .
: y = u ∙ v = ∙ .
2 68: : y′ =3 + x.
:
1). : y′ 3 ∙ y = x.
2). , :
a 0. : y = u ∙ v.
a 1. : =3 =3ln| x | → u = = x 3.
: u , u (x) : u′ + P (x)∙ u =0 (. y = u (x)∙ v (x)!).
a 2. v: v = += + = +.
a 3. : y = u ∙ v = x 3∙ = x 3 x 2.
: y = u ∙ v = x 3 x 2 .
3 74: : y′ = .
:
1). : x′ ∙ x = y 2. y = y (x) x = x (y) !
2). , :
a 0. : x = u (y)∙ v (y).
a 1. : = =ln| y | → u = = y.
: u (. 2-68).
a 2. v: v = += + = y 2+.
a 3. : x = u ∙ v = y ∙ = y + y 3.
: x = u ∙ v = y + y 3 . : y =0 .
4 78: : xy′ + x 2+ xy = y.
:
1). : y′ + ∙ y = x. y = y (x) x = x (y) !
2). , :
a 0. : y = u (x)∙ v (x).
a 1. : = =ln| x | x → u = = xe x .
: u (. 2-68).
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a 2. v: v = += + = ex +.
a 3. : y = u ∙ v = xe x ∙ = x ∙( e x 1).
: y = u ∙ v = x ∙( e x 1) .
5 83: : y′ + y∙tgx = , y (0)=0.
:
1). .
2). , :
a 0. : y = u ∙ v.
a 1. : = =ln|cos x | → u = = cos x.
: u (. 2-68).
a 2. v: v = += + = tgx +.
a 3. : y = u ∙ v = cos x ∙ = sin x + cos x.
a 4. : 0= sin0+ cos0 → =0; y = sin x : y (0)=0.
: y = sin x + cos x ; y = sin x .
6 86: : y′ +4 xy =2 x ∙ ∙ . (1)
:
1). (1) .
2). , :
a 0. : z = y n+1;
a 1. : z′ +( n +1) P (x)∙ z =( n +1) Q (x), ( !): z′ + P 1(x)∙ z = Q 1 (x);
a 2. : z = u (x)∙ v (x).
a 3. : → u = .
a 4. v: v = +.
a 5. : z = u ∙ v = ∙ .
3). : , n = .
a 0. : z = y n+1, ( n +1)= ; : z = .
a 1. : z′ + 4 x ∙ z = 2 x ∙ , :
z′ +2 x ∙ z = x ∙ . (2)
a 2. : z = u (x)∙ v (x).
a 3. : = = x 2 → u = = .
a 4. v: v = += x 2+.
a 5. (2): z = u ∙ v = ∙ . (3)
a 6. : z = , (1): = ∙ .
: = ∙ .
7 92: : xy′ + y =2 x 2∙ ylny ∙ y′. (1)
:
1). : (1) y, y′. x = x (y): x′ + x =2 lny ∙ x 2. (2)
2). (2) , n =2.
a 0. : z = x n+1, ( n +1)= 1; : z = x 1.
a 1. : z′ z = 2 lny. (3)
a 2. : z = u (y)∙ v (y);
a 3. : = =ln y → u = = y.
: u , y >0.
a 4. v: v = = 2 += ln 2 y +;
a 5. (3): z = u ∙ v = y ∙ . (4)
a 6. : z = x 1, (1): xy =1.
: xy =1 .
8 95: : ydx+ dy =0, y =1. (1)
:
1). : (1) y, y′. x = x (y): x′ + x = x 3. (2)
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3). (2) , n =3.
a 0. : z = x n+1, ( n +1)= 2; : z = x 2.
a 1. : z′ 2 z = 1. (3)
a 2. : z = u (y)∙ v (y);
a 3. : =2 =2ln| y | → u = = y 2.
: u (. 2-68). : 2ln| y | = ln y 2.
a 4. v: v = = += +.
a 5. (3): z = u ∙ v = y 2∙ . (4)
a 6. : z = x 2, (1): x 2(y + y 2)=1.
a 7. (1): (1 + 12)=1 → =3, : x 2(y +3 y 2)=1.
: x 2(y + y 2)=1 ; : x 2(y +3 y 2)=1.
9 179: , (1,0), , , , .
:
1 19 : = O =(0, y y ′ ), .
1). : S = h, a b , h , :
▪ ( + ND)∙ D =2 S =3 → (y y ′ +y)∙ = 3; (1)
▪ ( + ND)∙ D =2 S =3 → (y y ′ +y)∙ = 3. (2)
-1.
2). (1), : y ′ y = .
a 0. : y = u ∙ v.
a 1. : =2 =2ln| x | → u = x 2.
a 2. v: v = +=3 + = x 3+;
a 3. : y = u ∙ v = x 2∙(x 3+)= +C x 2.
a 4. : y = x 2, =1.
-2.
3). (2), : y ′ y = .
a 0. : y = u ∙ v.
a 1. : =2 =2ln| x | → u = x 2.
a 2. v: v = += 3 + = x 3+;
a 3. : y = u ∙ v = x 2∙( x 3+)=C x 2 . ջ , -1.
a 4. : y = x 2 , =1.
4). y = x 2, (. ).
: -1: y = x 2 ; -2: y = x 2 .
: , . : .
10 193: , . 1.5 /, 4 1/. 1 /? ?
:
: , , . , :
m∙v′ = k∙v, (1)
m ; k - . ( !).
: =μ , :
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= μ∙ dt. (2)
(2), : v = v 0 ∙e μ t, v 0=1.5 /. , . ( !), .
: t =4c v = 1 [/] → 1=1.5 ∙ e μ 4 . : (e μ) 4 = ≈ 0.67 e μ ≈ =λ.
, : v = v 0 ∙λt. v =1.5 ∙λt. , 1 /: 0.01=1.5 ∙λt, → t ≈ 50.
: dx =1.5 ∙λtdt. , : x 0=0. x =1.5 ∙ =1.5 ∙lnλ (0 λt) ≈ 15.
: , !
: : t ≈ 50. x ≈ 15 ( !).
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-2 | .10: 70, 71, 72, 75, 85, 87, 89, 94, 180, 198. |
1 70: : (1+ x 2) y′ = 2 xy +(1+ x 2)2. (1)
:
1). , : y′ + P (x)∙ y = Q (x), : y′ y = x 2+1. (2)
2). , :
a 0. : y = u ∙ v.
a 1. : : u = .
a 2. v: v = +.
a 3. : y = u ∙ v = ∙ .
3). : , : y′ + P (x)∙ y = Q (x)!
a 0. : y = u ∙ v.
a 1. : = =ln(x 2+1) → u = = x 2+1.
a 2. v: v = += + = x +.
a 3. : y = u ∙ v =(x 2+1)∙(x +).
: y = u ∙ v =(x 2+1)∙(x +) .
2 71: : y′ +2 y = e 3 x .
:
1). .
2). , :
a 0. : y = u ∙ v.
a 1. : = =2 x → u = = e 2 x .
a 2. v: v = += + = e 5 x +.
a 3. : y = u ∙ v = e 2 x ∙ = e 3 x + e 2 x .
: y = e 3 x + e 2 x .
3 72: : y′ + =2 lnx +1.
:
1). : y′ + y =2 lnx +1.
2). , :
a 0. : y = u ∙ v.
a 1. : = = lnx → u = = .
a 2. v: v = += + =2 + +. ( !): = = lnx , : v = x 2 lnx + + = x 2 lnx +.
a 3. : y = u ∙ v = ∙ = xlnx + .
: y = xlnx + .
4 75: : (1+ x 2) dx =(arctgy x) dy.
:
1). , y y′ . x x′: x′ + x = .
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2). , :
a 0. : y = u ∙ v.
a 1. : = = arctgy → u = = .
a 2. v: v = += +=[: arctgy=t ]= = +=[. !]= tet et += arctgy +.
a 3. : y = u ∙ v = ∙ = = arctgy 1+C
: y = arctgy 1+C .
5 85: : y′ = , y (1)=1.
:
1). , y y′ . x x′: x′ + x =2 lny +1.
2). , :
a 0. : x = u ∙ v.
a 1. : = = lny → u = = .
a 2. v: v = += + =2 + +. 3 72, : v = y 2 lny +.
a 3. : x = u ∙ v = ∙(y 2 lny +) = ylny + .
a 4. : x = ylny + , =1.
: x = ylny + ; : x = ylny + .
6 87: : dy =(y2ex y) dx. (1)
:
1). : y =0. (1): y′ + y = e x∙ y 2. (2)
2). (2) , n =2.
a 0. : z = y n+1, ( n +1)= 1; : z = y 1.
a 1. : z′ z = e x. (3)
a 2. : z = u (x)∙ v (x);
a 3. : = = x → u = = e x.
a 4. v: v = = += x +;
a 5. (3): z = u ∙ v = e x ∙(і x). (4)
a 6. : z = y 1, (1): y 1= e x ∙(і x).
: ye x ∙(і x)=1 , y =0.
7 89: : y′ = yctgx + . (1)
:
1). : y =0. (1): y′ ctgxy = ∙ y 3. (2)
2). (2) , n =3.
a 0. : z = y n+1, ( n +1)= 2; : z = y 2.
a 1. : z′ + ctgx∙z = 2 . (3)
a 2. : z = u (x)∙ v (x);
a 3. : =2 =2 ln | sinx | → u = = .
a 4. v: v = = +=2 +=2 cosx +C;
a 5. (3): z = u ∙ v = (2 cosx +C). (4)
a 6. : z = y 2, (1): y 2= (2 cosx +C).
: sin 2 x = y 2(2 cosx +C) , y =0.
8 94: : 3 dy = (1+3 y 3) y∙sinxdx, y =1. (1)
:
1). : y =0. (1): y′ + sinx∙y = sinx∙y 4. (2)
2). , :
a 0. : z = y n+1, ( n +1)= 3; : z = y 3.
a 1. : z′ sinx∙z = 3 sinx. (3)
a 2. : z = u (x)∙ v (x);
a 3. : = = cosx → u = = e cosx.
a 4. v: v = = + = 3 + =
=3 ecosx +;
a 5. (3): z = u ∙ v = e cosx (3 ecosx +). (4)
a 6. : z = y 3, (1): y 3=C e cosx 3.
a 4. : y 3=4 e cosx 3, =4.
: y 3=C e cosx 3 ; : y 3=4 e cosx 3.
9 180: , (0,1), , , - , 1.
:
1 19 : = O = , .
1). : S = ah, a , h , :
▪ ∙ ND =2 S =2 → ∙ y =2; (1)
▪ T ∙ ND =2 S =2 → ∙ y =2 (2)
-1.
2). (1), : x ′ x = .
a 0. : x = u ∙ v.
a 1. : = =ln| y | → u = y.
a 2. v: v = +=2 + = y 2+.
a 3. : x = u ∙ v = y ∙(y 2+)= +C y.
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a 4. : x = y, =1.
-2.
3). (2), : x ′ x = .
a 0. : x = u ∙ v.
a 1. : = =ln| y | → u = y.
a 2. v: v = +=2 + = y 2+;
a 3. : x = u ∙ v = y ∙(і y 2)=C y . ջ , -1.
a 4. : x = y , =1.
4). x = y, (. : ).
: -1: x = y ; -2: x = y .
: , . : .
10 198: i R, L u : L∙ + R∙i = u. i t, u = Esinωt i = 0 t = 0 (L, R, E, ω ).
:
1). :
i′ + a ∙ i = b ∙ u: (1)
a = b = ( ).
2). , :
a 0. : i = z ∙ v.
a 1. : = a = at → z = = e at.
a 2. v: v = += b += bE +. : J= = [ , J] = eat ∙(a ∙ sinωt ω ∙ cosωt). : v = bE ∙J+, v = bE ∙J+ bE ∙= bE ∙(J+). !: , bE !
a 3. : i = u ∙ v = bE ∙ e at ∙(J+). (2)
a 4. : i (0)=0 → = → : i = bE ∙ (a ∙ sinωt ω ∙ cosωt + ω ∙ e at). a b : i = (R ∙ sinωt Lω ∙ cosωt + Lω ∙ ).
: i = (R ∙ sinωt Lω ∙ cosωt + Lω ∙ ) .
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