Giải thích các bước giải:
`1a,(2x-3)^2+(4x-5)(x-7)`
`=4x^2-12x+9+4x^2-33x+35`
`=8x^2-45x+44`
`b,(x-2)(x+1)(x+2)-(x-1)^3`
`=x^3+x^2-4x-4-x^3+3x^2-3x+1`
`=4x^2-7x-3`
`c,(2x+5)(5-2x)+(3x-7)(x+2)`
`=-4x^2+25+3x^2-x-14`
`=-x^2-x+11`
`d,(2x+4)^2-(3x-5)^2`
`=4x^2+16x+10-9x^2+30x-25`
`=-5x^2+46x-15`
`2a,(2x-3)(x+1)-2(x-1)^2=3`
`<=>2x^2+2x-3x-3-2x^2+4x-2=3`
`<=>3x-5=3`
`<=>x=8/3`
`b,(4x+5)(2x-1)-(x+2)^2=(x-3)(x+3)`
`<=>8x^2-4x+10x-5-x^2-4x-4=x^2-9`
`<=>7x^2+2x=x^2`
`<=>6x^2+2x=0`
`<=>2x(3x+1)=0`
`<=>x=0` hoặc `x=-1/3`
`c,(x-2)^2+(x+3)^2=(x+1)^2+15`
`<=>2x^2+2x+13=x^2+2x+1+15`
`<=>x^2-16+13=0`
`<=>x^2=3`
`<=>x=` `+-`$\sqrt[]{3}$
Vậy .....................
