bài 1:
\(1.\left(5x+1\right)^2=25x^2+2\cdot5x\cdot1+1^2=25x^2+10x+1\)
\(2.\left(2x+3\right)^2=4x^2+2\cdot2x\cdot3+3^2=4x^2+12x+9\)
\(3.\left(2x-1\right)^2=4x^2-2\cdot2x\cdot1+1^2=4x^2-4x+1\)
\(4.\left(3x-2\right)^2=9x^2-2\cdot3x\cdot2+2^2=9x^2-12x+4\)
\(5.\left(x+2y\right)^2=x^2+2\cdot x\cdot2y+4y^2=x^2+4xy+4y^2\)
\(6.\left(x+5y\right)^2=x^2+2\cdot x\cdot5y+25y^2=x^2+10xy+25y^2\)
\(7.\left(x-2y\right)^2=x^2-2\cdot x\cdot2y+4y^2=x^2-4xy+4y^2\)
\(8.\left(2x-y\right)^2=4x^2-2\cdot2x\cdot y+y^2=4x^2-4xy+y^2\)
bài 2:
\(1.\left(3x\right)^2-y^2=\left(3x-y\right)\left(3x+y\right)\)
\(2.x^2-\left(2y\right)^2=\left(x-2y\right)\left(x+2y\right)\)
\(3.\left(2x\right)^2-y^2=\left(2x-y\right)\left(2x+y\right)\)
\(4.\left(3x-y^2\right)\left(3x+y^2\right)^{}=\left(3x\right)^2-\left(y^2\right)^2=9x^2-y^4\)
\(5.\left(x^2-2y\right)\left(x^2+2y\right)=\left(x^2\right)^2-\left(2y\right)^2=x^4-4y^2\)
\(6.\left(x^2-y^2\right)\left(x^2+y^2\right)=\left(x^2\right)^2-\left(y^2\right)^2=x^4-y^4\)
bài 3:
\(1.\left(3x+y\right)^2+\left(x-y\right)^2\)
\(=9x^2+6xy+y^2+x^2-2xy+y^2\)
\(=10x^2+4xy+2y^2\)
\(2.-\left(x+5\right)^2-\left(x-3\right)^2\)
\(=-\left(x^2+10x+25\right)-\left(x^2-6x+9\right)\)
\(=-x^2-10x-25-x^2+6x-9\)
\(=-2x^2-4x-34\)
\(3.\left(3x-2\right)^2-\left(3x-1\right)^2\)
\(=\left(3x-2+3x-1\right)\left(3x-2-3x+1\right)\)
\(=\left(6x-3\right)\cdot\left(-1\right)=-6x+3\)
bài 4:
\(1.x\left(1-x\right)+\left(x-1\right)^2\)
\(=x-x^2+x^2-2x+1\)
\(=-x+1\)
\(4.\left(x-3\right)^2-x^2+10x-7\)
\(=x^2-6x+9-x^2+10x-7\)
\(=4x+2\)
bài 5:
\(1.4x^4-4x^2+1=\left(2x^2\right)^2-2\cdot2x^2\cdot1+1^2=\left(2x^2-1\right)^2\)
\(2.4x^2-12x+9=\left(2x\right)^2-2\cdot2x\cdot3+3^2=\left(2x-3\right)^2\)
\(3.36+x^2-12x=x^2-12x+36\)
\(=x^2-2\cdot x\cdot6+6^2=\left(x-6\right)^2\)
em cần giải gấp bài 3 chi tiết mọi người giúp em với ạ. Làm bài dưới dạng phân số ạ em cần gấp
