whom you met at the gate, was a tiger-tamer

whose car is very good, works in factory that's very far from home

whom they want to see, is preparing lunch for everyone

x mũ 2018 =x nhân 2018

NaOH: Natri hiđroxit

Na2O:natri oxit

a: Xét ΔADM và ΔCBN có 

AD=CB

\(\widehat{DAM}=\widehat{BCN}\)

AM=CN

Do đó: ΔADM=ΔCBN

Suy ra: DM=BN

27: \(\sqrt{\dfrac{81}{25}}-\dfrac{1}{5}\left(-3+\sqrt{16}\right)^{20}\cdot\left(-2\right)^3\)

\(=\dfrac{9}{5}-\dfrac{1}{5}\cdot\left(-8\right)\)

\(=\dfrac{9}{5}+\dfrac{8}{5}=\dfrac{17}{5}\)

28: \(\sqrt{\sqrt{16}}-\sqrt{\sqrt{81}}=2-3=-1\)

Em cần giúp câu nào hả em? Em nên chụp 1-2 ý cho 1 lần hỏi nhá, như thế mọi người sẽ dễ dàng giúp em hơn

13

a, \(3x-4=-x+8\)

\(< =>3x+x=8+4\)

\(< =>4x=12\)

\(< =>x=\frac{12}{4}=3\)

b, \(\frac{2x+1}{6}+\frac{x-7}{12}=10\)

\(< =>\frac{2\left(2x+1\right)}{12}+\frac{x-7}{12}=\frac{120}{12}\)

\(< =>4x+2+x-7=120\)

\(< =>5x=120+5=125\)

\(< =>x=\frac{125}{5}=\frac{5^3}{5}=5^2=25\)

13

c,\(\left(x+1\right)^2-\left(x-1\right)^2=12\)

\(< =>x^2+2x+1-x^2+2x-1=12\)

\(< =>4x=12< =>x=\frac{12}{4}=3\)

d,\(3\left(x-1\right)< x+5\)

\(< =>3x-3< x+5\)

\(< =>3x-x< 5+3=8\)

\(< =>x< \frac{8}{2}=4\)

2.B

3.C

4.A