good

dễ vậy

Đoan OB dài: 8 + 2 = 10(cm)

Sai chỗ nào nhớ nhắn mình nha

m) 6x - 9y

<=> 3(2x - 3y)

n) 3xy² - 9x²y

<=> 3xy(y - 3x)

o) x(y - 6) + y(6 - y)

<=> x(y - 6) - y(y - 6)

<=> (-x - y)(6 + y)

p) x(3x - 1) + 2(1 - 3x)

<=> x(3x - 1) - 2(3x - 1)

<=> (-x - 2)(1 - 3x)

q) y(3x - 1) - 2(1 - 3x)

<=> y(3x - 1) + 2(3x - 1)

<=> (y + 2)(3x - 1)

r) x²(x - 3) + 4(3 - x)

<=> x²(x - 3) - 4(x - 3)

<=> (x² - 4)(x - 3)

s) x²y - 2xy + y

<=> x² - 2xy + y²

<=> (x - y)²

t) x²(x - 7) + 4x(7 - x) + 4(x - 7)

<=> x²(x - 7) - 4x(x - 7) + 4(x - 7)

<=> (x² - 4x + 4)(x - 7)

ok

PT: 4P + 5O₂ → 2P₂O₅.

Ta có: n_P= 9,3/31=0,3(mol)

Theo PT: n_O2= 5/4 . n_P=5/4 . 0,3=0,375(mol)

=> V_O2=0,375.22,4=8,4(lít)

Theo PT: n_P2O5=1/2 . n_P=1/2 . 0,3=0,15(mol)

=> m_P2O5= 0,15.142=21,3(g)

-_-