Question

tìm x

a/ 2x(x-5)-x(3+2x)=26

b/ 49x²-81=0

thank trước nha

Answer 1

b . 49x^2 - 81 = 0 

=> 49x^2 = 81 

rồi giải ra nhé 

Answer 2

a ) 2x ( x - 5 ) - x ( 3 + 2x ) = 26

2x² - 10x - 3x - 2x² = 26

- 13x = 26

x = 26 : ( -13 )

x = -2

b) 49x² - 81 = 0

( 7x - 9 )( 7x + 9 ) = 0

Th1 :

7x - 9 = 0

7x = 9

x = \(\frac{9}{7}\)

Th2

7x + 9 = 0

7x = -9

x = \(-\frac{9}{7}\)

Vay x = \(\frac{9}{7}\) hoac x = \(-\frac{9}{7}\)

Answer 3

bn này k bao gio tra cong ng khac, ngu j ma lam