Question

[Thanh Huyền]

giúp em cách làm gấp với ạ 

Answer 1

[Lấp La Lấp Lánh]

Bài 1:

a) \(=4x^2-20x-4x^2+7x-3+24x=11x-3\)

b) \(=y^2-9x^2+18xy-9x^2-18xy-9y^2=-18x^2-8y^2\)

c) \(=x^3+2x^2-x-2-x^3+8=2x^2-x+6\)

d) \(=1+4x+4x^2-2x-2+4x^2+x^2-2x+1=8x^2\)

Bài 2:

c) \(=64-\left(x^2-4xy+4y^2\right)=64-\left(x-2y\right)^2=\left(8-x+2y\right)\left(8+x-2y\right)\)

d) \(=x\left(x-3\right)-4\left(x-3\right)=\left(x-3\right)\left(x-4\right)\)

e) \(=\left(x^4+16x^2+64\right)-16x^2=\left(x^2+8\right)^2-16x^2=\left(x^2-4x+8\right)\left(x^2+4x+8\right)\)

f) \(=\left(a^4+4a^2b^2+4b^4\right)-4a^2b^2=\left(a^2+2b^2\right)^2-4a^2b^2=\left(a^2-2ab+2b^2\right)\left(a^2+2ab+2b^2\right)\)

g) \(=3x\left(x-2\right)-2\left(x-2\right)=\left(x-2\right)\left(3x-2\right)\)

Answer 2

[Lấp La Lấp Lánh]

Bài 3:

\(=47^2-2.47.37+37^2=\left(47-37\right)^2=10^2=100\)

Bài 4:

\(\Rightarrow\left(x^2-x+\dfrac{1}{4}\right)+\left(y^2+y+\dfrac{1}{4}\right)=0\Rightarrow\left(x-\dfrac{1}{2}\right)^2+\left(y+\dfrac{1}{2}\right)^2=0\)

\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\y=-\dfrac{1}{2}\end{matrix}\right.\)