a) (x - 5)² - x(x - 4) = 0

x² - 10x + 25 - x² + 4x = 0

-6x + 25 = 0

6x = 25

x = 25/6

b) x² - 3x = 5(x - 3)

x² - 3x = 5x - 15

x² - 3x - 5x + 15 = 0

(x² - 3x) - (5x - 15) = 0

x(x - 3) - 5(x - 3) = 0

(x - 3)(x - 5) = 0

x - 3 = 0 hoặc x - 5 = 0

*) x - 3 = 0

x = 3

*) x - 5 = 0

x = 5

Vậy x = 3; x = 5

1. She was surprised when she found a golden coin in the garden. (when)

2. I will go shopping as soon as I find my wallet (as soon as)

3. He made a quick phone call to a client before he left the office. (before)

4. After he had mowed the lawn, he took a rest. (after)

1. She was surprised when she found a golden coin in the garden.

2. I will go shopping right after as soon as I find my wallet.

3. Before he made a quick phone call to a client, he left the office.

4. He took a rest after he mowed the lawn.

a: ĐKXĐ: x∉{1;-1}

b: Ta có: \(C=\frac{x}{2x-2}+\frac{x^2+1}{2-2x^2}\)

\(=\frac{x}{2\left(x-1\right)}-\frac{x^2+1}{2\cdot\left(x-1\right)\left(x+1\right)}\)

\(=\frac{x\left(x+1\right)-x^2-1}{2\left(x-1\right)\left(x+1\right)}=\frac{x-1}{2\left(x-1\right)\left(x+1\right)}=\frac{1}{2\left(x+1\right)}\)

c: \(C=\frac12\)

=>\(\frac{1}{2\left(x+1\right)}=\frac12\)

=>x+1=1

=>x=0(nhận)

d: C>0

=>\(\frac{1}{2\left(x+1\right)}>0\)

=>2(x+1)>0

=>x+1>0

=>x>-1

Kết hợp ĐKXĐ, ta được: \(\begin{cases}x>-1\\ x<>1\end{cases}\)

Bạn xem lại đề. Có vẻ phương trình đã cho không đúng.

M=(x-y)²-2x-2y

= x²-2xy+y²-2(x+y)

= x²+2xy+y²-2(x+y)-4xy

= (x+y)²-2(x+y)-4xy

= 5²-2.5-4.6

= 25-10-24

= -9

help me

Cc

Một mảnh đất chữ nhật có chiều dài hơn chiều rộng 6.8m. Nếu ta bớt mỗi chiều đi 0.2m thì chu vi mới gấp 5 lần chiều dài mới. Tính diện tích mảnh đất đó.

giúp tui