Giải thích các bước giải:
`a, \ (x-8)^2-x(x+4)=0`
`<=> x^2-16x+64-x^2-4x=0`
`<=> -20x=-64`
`<=> x=16/5`
Vậy `x=16/5`
`b, \ x^2-25=(x+3)(5-x)`
`<=> (x-5)(x+5)-(x+3)(5-x)=0`
`<=> (x-5)(x+5)+(x+3)(x-5)=0`
`<=> (x-5)(x+5+x+3)=0`
`<=> (x-5)(2x+8)=0`
`<=> [(x-5=0),(2x+8=0):} <=> [(x=5),(x=-4):}`
Vậy `x in {-4;5}`
`c, \ x(x-4)+10x+5=0`
`<=> x^2-4x+10x+5=0`
`<=> x^2+6x+5=0`
`<=> x^2+x+5x+5=0`
`<=> x(x+1)+5(x+1)=0`
`<=> (x+1)(x+5)=0`
`<=> [(x+1=0),(x+5=0):} <=> [(x=-1),(x=-5):}`
Vậy `x in {-1;-5}`
