Question

tìm x:

a)2x^2+3(x^2-1)=5x(x+1)

b)2x(5-3x)+2x(3x-5)-3(x-7)=3

c)3x(x+1)-2x(x+2)=-1-x

Answer 1

a, 2x^2+3x^2-3=5x^2+5

<=> 2x^2+3x^2-3=5x^2+5x

<=> 5x^2-5x^2-5x=3

<=> -5x=3

<=> x = 3/-5=-0,6

Answer 2

b, 2x(5-3x)+2x(3x-5)-3(x-7)=3

<=> 10x-6x^2+6x^2-10x-3x+21=3

<=> -3x=-18

<=> x=18/3=8

Answer 3

c, 3x(x+1)-2x(x+2)=-1-x

<=> 3x^2+3x-2x^2-4x=-1-x

<=> 3x^2+3x-2x^2-4x+x=-1

<=> 1-1+x=-1

<=>x=-1-1+1

<=>x=-1