Question

Tìm x biết

x²-4x+4=25

Answer 1

x² - 4x + 4 = 25

x² - 4x       = 25 - 4

x² - 4x       =  21

x²              = 21 + 4x

x.x             = 21 + 4x

\(\Rightarrow\) 3x        = 21

        x        = 21 : 3

        x        = 7

Answer 2

pt<=>(x+2)²=25=>x+2=5 hoac x+2=-5=>x=3 hoac x=-7

Answer 3

x^2-4x+4=25

x^2-4x-21=0

x^2-7x+3x-21=0

x(x-7)+3(x-7)=0

(x-7)(x+3)=0

x-7=0 hoặc x+3=0

x=7 ,x=-3

Answer 4

X = 7 nha