Đáp án:
3. `(2x + 6)/(3x^2 - x) : (x^2 + 3x)/(1 - 3x)`
`= [2(x + 3)]/[x(3x - 1)] : [x(x + 3)]/(1 - 3x)`
`= [2(x + 3)]/[x(3x - 1)] . (1 - 3x)/[x(x + 3)]`
`= [2(x + 3)(1 - 3x)]/[x^2(x + 3)(3x - 1)]`
`= (-2)/(x^2)`
4. `(1 - 4x^2)/(x^2 + 4x) : (4x - 2)/(3x)`
`= [(1 - 2x)(1 + 2x)]/[x(x + 4)] : [2(2x - 1)]/(3x)`
`= [(1 - 2x)(1 + 2x)]/[x(x + 4)] . (3x)/[2(2x - 1)]`
`= [3x(1 - 2x)(1 + 2x)]/[2x(x + 4)(2x - 1)]`
`= [-3(2x + 1)]/[2(x + 4)]`
Giải thích các bước giải:
