Question

Tìm x:

a,2.{x+5}-x^2-5=0

b,2x.{x-5}-x.{3+2x}=26

c,{x+7}²-x.{x-3}=12

d,9.{x-2018}-x+2018=0

e,4x.{x+1}+{3x-2}.{3x+2}=15

Answer 1

b,2x.(x-5)-x.(3+2x)=26

2x² - 10x - 3x - 2x² = 26

-13x = 26

x = -2

c, (x+7)²-x.(x-3)=12

x² +14x +49 - x² + 3x = 12

17x + 49 = 12

17x = - 37

x = \(\dfrac{-37}{17}\)

d, 9( x -2018) - x+ 2018 =0

9( x -2018) - (x -2018) = 0

( 9-1)(x -2018) = 0

8( x -2018) = 0

x -2018 = 0

x = 2018

Answer 2

a: =>2x+10-x^2-5=0

=>-x^2+2x+5=0

=>\(x\in\left\{1+\sqrt{6};1-\sqrt{6}\right\}\)

e: =>4x^2+4x+9x^2-4=15

=>13x^2+4x-19=0

=>\(x\in\left\{\dfrac{-2+\sqrt{251}}{13};\dfrac{-2-\sqrt{251}}{13}\right\}\)