Question

tìm xϵz , biết :

a) 2x² - 3 = 29

b) -6x - (-7) = 25 

c) 46 - (x - 11 ) = -48

Answer 1

a) 2x²-3=29

2x²=32

x²=16

=>x=±4

b)-6x-(-7)=25

=>-6x=18

=>x=-3

c)46-(x-11)=-48

=> x-11=46+48

=>x-11=94

=>x=94+11=105

Answer 2

a) 2 . x² - 3 = 29

= 2 . x² = 29 + 3 = 32

= x² = 32 : 2 = 16

= x² = 4² ; -4²

= x = 4 ; -4

 

Answer 3

a/ 2x^2 - 3 = 29

2x^2 = 32

x^2 = 16

x = 4;-4

b/ -6x - (-7) = 25

‐6x +7 =25

‐6x = 18

x = ‐3

c/ 46 ‐ ﴾x‐11﴿ = ‐48

46 ‐x +11 = ‐48

46 ‐x = ‐59

x = 105

Answer 4

a) 2x^2 - 3 = 29

<=> 2x^2 = 29 + 3

<=> 2x^2 = 32

<=> x^2 = 32 : 2

<=> x^2 = 16

Suy ra: x=4 hoặc x=-4

b)-6x - (-7) = 25

<=> -6x + 7 = 25

<=> -6x = 25 - 7

<=> -6x = 18

<=> x = 18 : (-6)

<=> x = -3

c) 46 - (x - 11) = -48

<=> x - 11 = 46 - (-48)

<=> x - 11 = 46 + 48

<=> x - 11 = 94

<=> x = 94 + 11

<=> x = 105