help mk vs mk dang can gap plssssssssssssssssssssssssssssssssssss
\(Bài6\)
\(a.=4\cdot49^2+8\cdot49+4=4\cdot2401+8\cdot49+4\)
\(=9604+392+4=10000.\)
\(b.=99^3+3\cdot99^2+3\cdot99+1=970299+3\cdot9801+3\cdot99+1\)
\(=970299+29403+297+1=1000000.\)
\(c.=23^3-9\cdot23^2+27\cdot23-26=12167-9\cdot529+27\cdot23-26\)
\(=12167-4761+621-26=8001.\)
\(d.=4x^2-12x+9-8x^2+32x-30+4x^2-20x+25\)
\(=4x^2-8x^2+4x^2-12x+32x-20x+9-30+25\)
\(=4.\)
\(Bài7\)
\(a.\left(x-2\right)\left(x+3\right)+\left(x-4\right)\left(x-5\right)=x^2+x-6+x^2-9x+20\)
\(=2x^2-8x+14.\)
\(b.\left(x-y\right)\left(x+y\right)-\left(x-y\right)^2=x^2-y^2-x^2+2xy-y^2\)
\(=-2y^2+2xy.\)
\(c.\left(x-4\right)\left(x+2\right)+\left(3-x\right)\left(2+x\right)=x^2-2x-8+6+x-x^2\)
\(=-x-2.\)
\(d.\left(2x-1\right)^2-\left(3x+1\right)^2=4x^2-4x+1-9x^2-6x-1\)
\(=-5x^2-10x.\)
