Đáp án+Giải thích các bước giải:
`a)` `MTC:30x^4y^3`
`2/{15x^3y^2}={2.2xy}/{15x^3y^{2}.2xy}={4xy}/{30x^4y^3}`
`y/{10x^4y^3}={y.3}/{10x^4y^{3}.3}={3y}/{30x^4y^3}`
`b)` `MTC:120x^4y^5`
`{3x+2}/{10x^4y}={(3x+2).12y^4}/{10x^4y.12y^4}={(3x+2).12y^4}/{120x^4y^5}`
`5/{8x^2y^2}={5.15x^2y^3}/{8x^2y^{2}.15x^2y^3}={75x^2y^3}/{120x^4y^5}`
`c)` Ta có:
`{7x-1}/{2x^2+6x}={7x-1}/{2x(x+3)}`
`{3-2x}/{x^2-9}={3-2x}/{(x-3)(x+3)}`
`MTC:2x(x-3)(x+3)`
`{7x-1}/{2x^2+6x}={(7x-1)(x-3)}/{2x(x-3)(x+3)}`
`{3-2x}/{x^2-9}={(3-2x).2x}/{2x(x-3)(x+3)}`
`d)` Ta có:
`5/{3x^3-12x}=5/{3x(x^2-4)}=5/{3x(x-2)(x+2)}`
`3/{(2x+4)(x+3)}=3/{2(x+2)(x+3)}`
`MTC:6x(x-2)(x+2)(x+3)`
`5/{3x^3-12x}={5.2(x+3)}/{3x(x-2)(x+2).2(x+3)}={10(x+3)}/{6x(x-2)(x+2)(x+3)}`
`3/{(2x+4)(x+3)}={3.3x(x-2)}/{2(x+2)(x+3).3x(x-2)}={9x(x-2)}/{6x(x-2)(x+2)(x+3)}`
