Đáp án + Giải thích các bước giải:
Bài `2:`
`a, \ (x-2)^2-(x-3)(x+3)`
`=x^2-4x+4-(x^2-9)`
`=x^2-4x+4-x^2+9`
`=(x^2-x^2)-4x+(4+9)`
`=-4x+13`
`b, \ 2(2x-2)(3x+2)+(3x+2)^2+(2x-2)^2`
`=(3x+2)^2+2.(3x+2).(2x-2)+(2x-2)^2`
`=(3x+2+2x-2)^2`
`=(5x)^2=25x^2`
`c, \ (4x-3)(x-5)-2x(2x-11)`
`=4x^2-20x-3x+15-4x^2+22x`
`=(4x^2-4x^2)-(20x+3x-22x)+15`
`=-x+15`
Bài `3:`
`a, \ 24^2+76^2+48.76`
`=24^2+2.24.76+76^2`
`=(24+76)^2=100^2=10000`
`b, \ 77^2+23^2-46.77`
`=77^2-2.77.23+23^2`
`=(77-23)^2=54^2`
`=(50+4)^2=50^2+2.50.4+4^2`
`=2500+400+16=2916`
