Question

Ai làm giúp mk vs

Answer 1

Bài nào?

Answer 2

a) x²-y²+3x+3y

=(x+y)(x-y)+3(x+y)

=(x+y)(x-y+3)

b) x²+2x+1-y²

=(x+1)²-y²

=(x-y+1)(x+y+1)

Answer 3

a) (x-2)²

= x²-2.x.2 + 2²

=x²-4x+4

b) \(\frac{5x+3}{x+2}+\frac{7}{x+2}=\frac{5x+3+7}{x+2}=\frac{5x+10}{x+2}=\frac{5\left(x+2\right)}{x+2}=5\)

c) \(\frac{2a}{a-1}+\frac{a}{1-a}=\frac{2a}{a-1}-\frac{a}{a-1}=\frac{2a-a}{a-1}=\frac{a}{a-1}\)

Answer 4

x(x-3)-x²+9=0

x(x-3)-(x²-9)=0

x(x-3)-(x-3)(x+3)=0

(x-3)(x-x-3)=0

-3(x-3)=0

=> x=3

Answer 5

a) \(A=\frac{1-6x+9x^2}{x\left(3x-1\right)}=\frac{1^2-2.3x+\left(3x\right)^2}{x\left(3x-1\right)}=\frac{\left(1-3x\right)^2}{-x\left(1-3x\right)}=\frac{1-3x}{-x}=\frac{3x-1}{x}\)

b)

Answer 6

x²-y²+3x+3y=(x+y)(x-y)+3(x+y)=(x+y)(x-y-3)

Answer 7

\(x^2+2x+1-y^2=\left(x^2+2x+1\right)-y^2=\left(x+1\right)^2-y^2=\left(x+1-y\right)\left(x+1+y\right)\)

Answer 8

(x-2)²=x²-4x+4. Mình không hiểu cái câu này có ý nghĩa gì, 1 HĐT thôi mà

Answer 9

\(\frac{5x+3}{x+2}+\frac{7}{x+2}=\frac{5x+3+7}{x+2}=\frac{5x+10}{x+2}=\frac{5\left(x+2\right)}{x+2}=5\)

Đề này thì 10Đ khỏe

Answer 10

\(\frac{2a}{a-1}+\frac{a}{1-a}=\frac{2a}{a-1}+\frac{-a}{a-1}=\frac{2a-a}{a-1}=\frac{a}{a-1}\)

Answer 11

\(x\left(x-3\right)-x^2+9=0\Leftrightarrow x\left(x-3\right)-\left(x^2-9\right)=0\Leftrightarrow x\left(x-3\right)-\left(x+3\right)\left(x-3\right)=0\Leftrightarrow\left(x-x+3\right)\left(x-3\right)=0\Leftrightarrow3\left(x-3\right)=0=>x=3\)