7/31/2019 Chuyn 6. H phng trnh cha cn thc - m - loggarit

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Chuyen e 6: HE PHNG TRNH CHACAN THC-MU VA LOGART

Cac phng phap giai thng s dung

1. Phng phap 1:S dung cac phep bien oi tng ng va phep the

V du : Giai cac he phng trnh

1)2 3

9 3

x 1 2 y 1

3 log (9x ) log y 3

+ =

=6)

=+

=

4)(log)(log

)3

1()3(

22

2

yxyx

yxyx

2)

=+

=

25

11

log)(log

22

4

4

1

yx

yxy

7)y

3

3 4 x( x 1 1)3

x

y log x 1

+ =

+ =

3)

=+

+

=+

y

yy

x

xx

x

22

24

452

1

23

8)

=

=+

1loglog

4

44

8log8log

yx

yxxy

4)

=+

+=

102

1

yx

xxy9)

x 4 y 3 0

log x log y 04 2

+ =

=

5) 10)

=+

=+

4loglog2

5)(log

24

22

2

yx

yx

=+

=

3

644.2

yx

yx

11)

=+

=

2)(log

11522.3

5yx

yx

2. Phng phap 2:at an phu

V du : Giai cac he phng trnh

1)

=+

=+

20

5

yyxx

yx2)

13 2 5

4 6.3 2

y x

x y

+ =

0 + =

3)2

log log 2

3 20 log

x y

y

y x

x x y x

+ =

= +4)

=

=+

++

+

162.32

1424

2222

22222

yxy

yyxx

5)

=+++

=+

411

3

yx

xyyx6)

=

=+

1log1log3

5log53log

32

32

yx

yx

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