Đáp án:
Giải thích các bước giải:
\(a,\ 2x-2=8\\ ⇔2x=10\\ ⇔x=5\\ \text{Vậy x = 5}\\ b,\ 7-2x=1\\ ⇔2x=7-1\\ ⇔2x=6\\ ⇔x=3\\ \text{Vậy x = 3}\\ c,\ 8:x+2=10\\ ⇔8:x=10-2\\ ⇔8:x=8\\ ⇔x=1\\ \text{Vậy x = 1}\\ d,\ x:2+5=14\\ ⇔x:2=14-5\\ ⇔x:2=9\\ ⇔x=9\times 2=18\\ \text{Vậy x = 18}\\ e,\ 9-x:2=6\\ ⇔x:2=9-6\\ ⇔x:2=3\\ ⇔x=3\times 2=6\\ \text{Vậy x = 6}\\ f,\ 18-15:x=15\\ ⇔15:x=18-15\\ ⇔15:x=3\\ ⇔x=15:3=5\\ \text{Vậy x = 5}\\ g,\ 2(2+2x)=20\\ ⇔2+2x=20:2\\ ⇔2+2x=10\\ ⇔2x=10-2\\ ⇔2x=8\\ ⇔x=4\\ \text{Vậy x = 4}\\ h,\ (x-34).15=0\\ ⇔x-34=0\\ ⇔x=34\\ \text{Vậy x = 34}\\ i,\ 18(x-16)=18\\ ⇔x-16=18:18\\ ⇔x-16=1\\ ⇔x=17\\ \text{Vậy x = 17}\\ k,\ (30+x).4=140\\ ⇔30+x=140:4\\ ⇔30+x=35\\ ⇔x=35-30=5\\ \text{Vậy x = 5}\\ l,\ (x+7).35=2.35\\ ⇔(x+7).35=70\\ ⇔x+7=70:35\\ ⇔x+7=2\\ ⇔x=2-7=(-5)\\ \text{Vậy x = -5}\\ m,\ 45.(2x-4).13=0\\ ⇔45.(2x+4)=0\\ ⇔2x-4=0\\ ⇔2x=4\\ ⇔x=4:2=2\\ \text{Vậy x = 2}\\ n,\ 2.(3+x)+5=67\\ ⇔2.(3+x)=67-5\\ ⇔2.(3+x)=62\\ ⇔3+x=62:2\\ ⇔3+x=31\\ ⇔x=31-3=28\\ \text{Vậy x = 28}\\ \text{Nâng cao:}\\ a,\ 450:(x+3)-13=37\\ ⇔450:(x+3)=37+13\\ ⇔450:(x+3)=50\\ ⇔x+3=450:50\\ ⇔x+3=9\\ ⇔x=9-3=6\\ \text{Vậy x = 6}\\ b,\ 5+6(2x+3)=35\\ ⇔6(2x+3)=35-5\\ ⇔6(2x+3)=30\\ ⇔2x+3=30:6\\ ⇔2x+3=5\\ ⇔2x=5-3\\ ⇔2x=2\\ ⇔x=2:2=1\\ \text{Vậy x = 1}\\ c,\ 96-3(x+1)=42\\ ⇔3(x+1)=96-42\\ ⇔3(x+1)=54\\ ⇔x+1=54:3\\ ⇔x+1=18\\ ⇔x=18-1=17\\ \text{Vậy x = 17}\\ d,\ 5(5-x)=0\\ ⇔5-x=0\\ ⇔x=5\\ \text{Vậy x = 5}\\ e,\ (x-11)(x+17)=0\\ ⇔\left[ \begin{array}{l}x-11=0\\x+17=0\end{array} \right.⇔\left[ \begin{array}{l}x=11\\x=-17\end{array} \right.\\ \text{Vậy x = 11 hoặc x = (-17)}\\ f,\ (x-3)(x-5)=0\\ ⇔\left[ \begin{array}{l}x-3=0\\x-5=0\end{array} \right.⇔\left[ \begin{array}{l}x=3\\x=5\end{array} \right.\\ \text{Vậy x = 3 hoặc x = 5}\\ g,\ (x-5)(x-7)=0\\ ⇔\left[ \begin{array}{l}x-5=0\\x-7=0\end{array} \right.⇔\left[ \begin{array}{l}x=5\\x=7\end{array} \right.\\ \text{Vậy x = 5 hoặc x = 7}\\ h,\ (x+3)(2+x)=0\\ ⇔\left[ \begin{array}{l}x+3=0\\2+x=0\end{array} \right.⇔\left[ \begin{array}{l}x=-3\\x=-2\end{array} \right.\\ \text{Vậy x = (-3) hoặc x = (-2)}\\ i,\ x+2x+3x-4x+12=48\\ ⇔x+2x+3x-4x=48-12\\ ⇔2x=36\\ ⇔x=36:2=18\\ \text{Vậy x = 18}\\ k,\ 57+x+3x-2x+13=100\\ ⇔x+3x-2x=100-57-13\\ ⇔2x=30\\ ⇔x=30:2=15\\ \text{Vậy x = 15}\\ l,\ 68-2x+5x+x=120\\ ⇔-2x+5x+x=120-68\\ ⇔4x=52\\ ⇔x=52:4=13\\ \text{Vậy x = 13}\)
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