Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
ä) ðîçâ’ÿçàòè ñèñòåìó ³ ï³äñòàâèòè çíàéäåí³ çíà÷åííÿ A 1 ,<br />
..., B 1 , ..., C 1 , ..., D 1 , ..., D r äî â³äïîâ³äíî¿ ôîðìóëè ðîçêëàäàííÿ.<br />
ϳñëÿ ðîçêëàäàííÿ íà åëåìåíòàðí³ äîäàíêè äðîáó, ³íòåãðóâàííÿ<br />
óñÿêîãî ïðàâèëüíîãî ðàö³îíàëüíîãî äðîáó çâîäèòüñÿ<br />
äî çíàõîäæåííÿ ³íòåãðàë³â âèäó:<br />
dx<br />
Mx + N<br />
I1<br />
= ∫ ³ I<br />
( x−<br />
a) m 2<br />
= ∫<br />
dx<br />
2<br />
,<br />
( x + px+<br />
q) n<br />
ïðî ÿê³ âæå éøëîñÿ.<br />
Ïðèêëàä 8.4.1. Çíàéòè ³íòåãðàë:<br />
∫<br />
− 4 + 3 + 6 −1<br />
dx .<br />
x − 5x + 6x<br />
4<br />
x<br />
3<br />
x<br />
2<br />
x x<br />
3 2<br />
Ðîçâ’ÿçàííÿ. Ïðèâîäèìî íåïðàâèëüíèé äð³á äî ïðàâèëüíîãî<br />
çà äîïîìîãîþ ä³ëåííÿ çâè÷àéíèì “ñòîâï÷èêîì”<br />
x 4 − 3 2 2<br />
4 x + 3 x + 6 x− 1 2 1<br />
= x + 1+<br />
x −<br />
− 5 + 6 − 5 + 6<br />
à) ðîçêëàäàºìî çíàìåííèê íà ìíîæíèêè<br />
3 2 3 2<br />
x x x x x x<br />
3 2 3<br />
x − 5x + 6 x = x( x − 5x+ 6) = x( x−2)( x− 3) ;<br />
á) çàïèñóºìî ðîçêëàäàííÿ ðàö³îíàëüíîãî äðîáó<br />
2<br />
2x −1<br />
A B C<br />
= + +<br />
3 2<br />
;<br />
x − 5x + 6x<br />
x x−2 x−3<br />
â) çâ³ëüíÿºìîñÿ â³ä çíàìåííèê³â<br />
( ) ( ) ( )<br />
2 2 2 2<br />
2 1 5 6 3 2<br />
x − = A x − x+ + B x − x + C x − x ;<br />
ã) ñêëàäàºìî ñèñòåìó ð³âíÿíü, ïðèð³âíþþ÷è êîåô³ö³ºíòè<br />
ïðè îäíàêîâèõ ñòåïåíÿõ x çë³âà ³ ñïðàâà. À ñàìå:<br />
;<br />
ä) ðîçâ’ÿçóºìî îäåðæàíó ñèñòåìó çà ôîðìóëàìè Êðàìåðà<br />
1 1 1 2 1 1<br />
1 1 1 1<br />
∆= 5 3 2 = 6 =−6, ∆<br />
A<br />
= 0 3 2 =− = 1,<br />
3 2 3 2<br />
6 0 0 −1 0 0<br />
1 2 1 1 1 2<br />
∆<br />
B<br />
= 5 0 2 = 21, ∆<br />
C<br />
= 5 3 0 =−34<br />
,<br />
6 −1 0 6 0 −1<br />
A 1 B 7 C 17<br />
A= ∆ =− , B = ∆ =− , C = ∆ = .<br />
∆ 6 ∆ 2 ∆ 3<br />
ßñíî, ùî ñèñòåìó ìîæíà ðîçâ’ÿçàòè é ³íøèìè ìåòîäàìè.<br />
Îñòàòî÷íî îòðèìàºìî<br />
x 4 3 2<br />
− 4 x + 3 x + 6 x −1 1 7 17<br />
∫ dx =<br />
3 2<br />
∫( x + 1)<br />
dx − ∫ dx − ∫ dx + ∫<br />
dx =<br />
x − 5x + 6x<br />
6 x 2 x−2 3 x−3<br />
ÂÏÐÀÂÈ<br />
1 2 1 7 17<br />
= x + x− ln x − ln x− 2 + ln x− 3 + c .<br />
2 6 2 3<br />
Çíàéòè ³íòåãðàëè:<br />
8.39.<br />
8.41.<br />
∫<br />
∫<br />
2<br />
xdx<br />
( x+ 1) ( x+<br />
4)<br />
2 2<br />
4<br />
xdx<br />
2<br />
( x − 1)( x+<br />
2)<br />
; 8.40.<br />
; 8.42.<br />
3x<br />
+ 2<br />
∫<br />
x x<br />
( + 1) 3<br />
5<br />
xdx<br />
3<br />
∫<br />
x − 1<br />
;<br />
dx ;<br />
2<br />
x : ⎧ A+ B+ C = 2,<br />
1 ⎪<br />
x : ⎨5A+ 3B+ 2C<br />
= 0,<br />
0<br />
x : ⎪<br />
⎩ 6A=−1;<br />
8.43.<br />
∫<br />
x +<br />
4<br />
3<br />
2<br />
8<br />
3<br />
x +<br />
2<br />
x + x<br />
dx ; 8.44.<br />
∫<br />
x + x +<br />
4 2<br />
x + 3x<br />
5 3<br />
2 6 1<br />
dx .<br />
278 279