\(A=3^1+3^2+3^3+...+3^{100}\)

\(3A=3^2+3^3+3^4+...+3^{101}\)

\(A=\left(3^{101}-3^1\right):2\)

Đề bài tìm x này thiếu dữ kiện bạn nhé. Xem lại đề bài.

Bài 23:

\(a.2^3-5^3:5^2+12\cdot2^2\)

\(=8-5+12\cdot4\)

\(=8-5+48\)

\(=3+48\)

\(=51\)

\(b.\) \(5\cdot\left[\left(85-35:7\right):8+90\right]-50\)

\(=5\cdot\left[\left(85-5\right):8+90\right]-50\)

\(=5\cdot\left[80:8+90\right]-50\)

\(=5\cdot\left[10+90\right]-50\)

\(=5\cdot100-50\)

\(=500-50=450\)

\(c.\) \(2\cdot\left[\left(7-3^3:3^2\right):2^2+99\right]-100\)

\(=2\cdot\left[\left(7-3\right):4+99\right]-100\)

\(=2\cdot\left[4:4+99\right]-100\)

\(=2\cdot\left[1+99\right]-100\)

\(=2\cdot100-100\)

\(=200-100=100\)

\(d.\) \(2^7:2^2+5^4:5^3\cdot2^4-3\cdot2^5\)

\(=2^5+5\cdot16-3\cdot32\)

\(=32+80-96\)

\(=112-96=16\)

\(e.\) \(\left(3^5\cdot3^7\right):3^{10}+5\cdot2^4-7^3:7\)

\(=3^{12}:3^{10}+5\cdot16-7^2\)

\(=3^2+80-49\)

\(=9+80-49\)

\(=89-49=40\)

\(f.\) \(3^2\cdot\left[\left(5^2-3\right):11\right]-2^4+2\cdot10^3\)

\(=9\cdot\left[\left(25-3\right):11\right]-16+2\cdot1000\)

\(=9\cdot\left[22:11\right]-16+2000\)

\(=9\cdot2-16+2000\)

\(=18-16+2000\)

\(=2+2000=2002\)

Bài 24:

\(a.\) \(70-5\cdot\left(x-3\right)=45\)

\(5\cdot\left(x-3\right)=70-45\)

\(5\cdot\left(x-3\right)=25\)

\(x-3=25:5\)

\(x-3=5\)

\(x=5+3\)

\(x=8\)

\(b.\) \(12+\left(5+x\right)=20\)

\(5+x=20-12\)

\(5+x=8\)

\(x=8-5\)

\(x=3\)

\(c.\) \(130-\left(100+x\right)=25\)

\(100+x=130-25\)

\(100+x=105\)

\(x=105-100\)

\(x=5\)

\(d.\) \(175+\left(30-x\right)=200\)

\(30-x=200-175\)

\(30-x=25\)

\(x=30-25\)

\(x=5\)

\(e.\) \(5\cdot\left(x+12\right)+22=92\)

\(5\cdot\left(x+12\right)=92-22\)

\(5\cdot\left(x+12\right)=70\)

\(x+12=70:5\)

\(x+12=14\)

\(x=14-12\)

\(x=2\)

\(f.\) \(95-5\cdot\left(x+2\right)=45\)

\(5\cdot\left(x+2\right)=95-45\)

\(5\cdot\left(x+2\right)=50\)

\(x+2=50:5\)

\(x+2=10\)

\(x=10-2\)

\(x=8\)

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Bạn không hỏi linh tinh nhé.

\(a.\) \(\left(-156\right)-\left(-26\right)=\left(-156\right)+26=130\)

\(b.\) \(\left(-156\right)-76=-\left(156+76\right)=-232\)

\(c.\) \(\left(-156\right)-\left(-28\right)-\left(-143\right)\)

\(=\left(-156\right)+28+143\)

\(=\left(-128\right)+143\)

\(=\left(143-128\right)=15\)

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