Question

Tìm số nguyên x biết

a) x . ( x + 3 ) = x . ( x + 2 )

b) x . ( 2x + 3 ) = x . ( x + 1 )

c) x . ( x - 3 ) = 2x -6

Answer 1

a. x.(x+3) = x.(x+2)

=> x² + 3x = x² + 2x

=> x²-x²+3x-2x=0

=> x=0

b. x(2x+3) = x(x+1)

=> 2x²+3x=x²+x

=> 2x²-x²+3x-x=0

=> x²+2x=0

=> x.(x+2)=0

=> x=0 hoặc x+2=0

=> x=0 hoặc x=-2

c. x.(x-3)=2x-6

=> x(x-3)=2.(x-3)

=> x(x-3)-2(x-3)=0

=> (x-3)(x-2)=0

=> x-3=0 hoặc x-2=0

=> x=3 hoặc x=2.

Answer 2

a. x.(x+3) = x.(x+2)

=> x² + 3x = x² + 2x

=> x²-x²+3x-2x=0

=> x=0

b. x(2x+3) = x(x+1)

=> 2x²+3x=x²+x

=> 2x²-x²+3x-x=0

=> x²+2x=0

=> x.(x+2)=0

=> x=0 hoặc x+2=0

=> x=0 hoặc x=-2

c. x.(x-3)=2x-6

=> x(x-3)=2.(x-3)

=> x(x-3)-2(x-3)=0

=> (x-3)(x-2)=0

=> x-3=0 hoặc x-2=0

=> x=3 hoặc x=2.