\(\Rightarrow5x^2-5x-x^2+5x-6=3\Rightarrow4x^2=9\Rightarrow x^2=\dfrac{9}{4}\Rightarrow\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=-\dfrac{3}{2}\end{matrix}\right.\)

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

ĐKXĐ: \(x\ge2\)

\(pt\Leftrightarrow2\sqrt{x-2}-\sqrt{x-2}-3\sqrt{x-2}=-1\)

\(\Leftrightarrow-2\sqrt{x-2}=-1\Leftrightarrow\sqrt{x-2}=\dfrac{1}{2}\)

\(\Leftrightarrow x-2=\dfrac{1}{4}\Leftrightarrow x=\dfrac{9}{4}\left(tm\right)\)

\(A=P.t=880.4.60.60=12672000\left(J\right)=3,52\left(kWh\right)\)

Nhiệt lượng tỏa ra trong 30 ngày: \(3,52.30=105,6\left(kWh\right)\)= 105,6 số

 Tiền điện phải trả: \(1000.105,6=105600\left(đồng\right)\)

\(p=\dfrac{F}{S}=\dfrac{P}{S}=\dfrac{10}{2}=5\left(Pa\right)\)

\(\left\{{}\begin{matrix}P=U.I\Rightarrow I=\dfrac{P}{U}=\dfrac{60}{220}=\dfrac{3}{11}\left(A\right)\\R=\dfrac{U}{I}=\dfrac{220}{\dfrac{3}{11}}=\dfrac{2420}{3}\left(\Omega\right)\end{matrix}\right.\)

\(A=P.t=60.60.60=216000\left(J\right)=0,06\left(kWh\right)\)

\(\left\{{}\begin{matrix}P=U.I\Rightarrow I=\dfrac{P}{U}=\dfrac{1100}{220}=5\left(A\right)\\R=\dfrac{U}{I}=\dfrac{220}{5}=44\left(\Omega\right)\end{matrix}\right.\)

\(A=P.t=1100.60.60=3960000\left(J\right)=1,1\left(kWh\right)\)

\(A=P.t=1100.30.2.60.60=237600000\left(J\right)=66\left(kWh\right)\)

Diện tích căn phòng: \(6\times9=54\left(m^2\right)=540000\left(cm^2\right)\)

Diện tích viên gạch: \(30\times30=900\left(cm^2\right)\)

Số viên gạch cần để lát căn phòng: \(540000:900=600\left(viên\right)\)