3 :
1) ;
2) ;
3) .
, . .
, f(x) . 5 f (x) = ln (x 1)2 0.5, ,
ln (x 1)20.5=0
: .
f (x) f (x) = g 1 (x) - g 2 (x), g 1 (x) = g 2 (x). g 1 (x) g 2 (x). 6 os (x) x + 1 = 0. , .
:
1. f(x) [a;b] (f (a) ∙ f (b) < 0), [a;b] f (x) = 0 ( 7).
2. f(x) [a;b] f'(x), f(x) , ( 8).
, , cos (x) x + 1 = 0 [1;2] ( 9). f(x) :
f(1) = cos (1) 1 + 1 = 0.54, f (2) = cos (2) 2 + 1 = -1.42,
[1;2] .
f'(x) = sin (x) [1;2] , , .
( 10):
1. n n .
2. n.
3. ai.
4. ai, x x.
( 11), x3 x + 1 = 0 3 . 3 1.
2 , , 2 0.
x x 1 , , 1.
x >= 0 f (x) = x3 x + 1 > 0, , .
f (0) = 1 > 0, f (-2) = -5 < 0, [2;0].
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( 12) f(x) x . , , , , .
, , . .
f (x) = 0 [ a; b ], f (a)∙ f (b) < 0. c = (a + b)/2. f(c)∙ f (b) < 0 ( 13), [c;b], . a c.
[a;b] c ( 13). f(c)∙ f () < 0, [a;c]. b c, [a;b].
, [a;b], f (a)∙ f (b) < 0 .
x * , n ε (bn - an < e). Î [ an; bn ] | - x * | < , ε Î [ an; bn ] ( 14). .
, ,
f(x) [a;b], . . b0 a0 = 1 ε = 10-6 n 20.
15 . a b, E. c. , f(x). fa fc .
f (x) = 0 x = φ(x). ( 16). x2 sin x = 0. , , :
x = x + x 2 sin x
x = √sin x
x = arc sin x2
.
:
xn = φ(xn -1),
φ(x) . , x 0 Î [ a; b ], :
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x 1 = j (x 0), x 2 = j (x 1), , xn = j (xn -1),
x*,
, .
y = x y = j (x) ( 17, ). = j (x) . x 0 Î [ a; b ]. y = j (x) 0 = j (x 0). , 0 y = x ( 1) x. y=x , 1= j (x 0). , () 0, 1, 1, 2, 2, 1, 2, , n *.
, , . , φ(x) 1 ( φ(x) y =x).
y = j (x) ( 17, ). 0, 1, 1, 2, 2 . , , . , φ(x) 1 ( φ(x) y = x).
18 , j (x) 1, , , .
, j (x), ( 19):
* x = j (x) [ a; b ] xn = j (xn -1). , xn = j (xn -1) Î [ a; b ] q (0< q <1), Î [ a; b ] | j (x)| ≤ q < 1, , x *, .. .
, , [ a; b ] ( 20):
,
, q < 1. cos (x) 3 x + 1 = 0, [0;1] ( 21).
, :
x = (cos(x) + 1)/3
j (x) = (cos(x) + 1)/3, | j (x)| = sin(x)/3. [0;1] sin(x) , x = 1. ,
0 Î [0;1].
x n = (cos(x n -1) + 1)/3 x 0 = 0 ( 22):
x1 = (cos(x0) + 1)/3 = (cos(0) + 1)/3 = 0.667
x2 = (cos(x1) + 1)/3 = (cos(0.667) + 1)/3 = 0.595
x3 = (cos(x2) + 1)/3 = (cos(0.595) + 1)/3 = 0.609
x4 = (cos(x3) + 1)/3 = (cos(0.609) + 1)/3 = 0.607
, .
( 23), n
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, q>0.5 ε xn xn1 xn x *. , , q=0.9 | xn x * | | xn xn -1 |.
, | xn x * | <= ε,
: