Question

K.(3x-1)(2x+7)-(x+1)(6x-5)=16
L.4x(x-7)=(x-7)
M.2(x+15)-x^2-5x=0
N.(x-2)^2-16=0

Answer 1

k: =>6x^2+21x-2x-7-6x^2+5x-6x+5=16

=>19x-x-2=16

=>18x=18

=>x=1

l: =>4x(x-7)-(x-7)=0

=>(x-7)(4x-1)=0

=>x=7 hoặc x=1/4

m: =>2x+30-x^2-5x=0

=>-x^2-3x+30=0

=>x^2+3x-30=0

=>\(x=\dfrac{-3\pm\sqrt{129}}{2}\)

n: =>(x-2-2)(x-2+2)=0

=>x(x-4)=0

=>x=0 hoặc x=4