\(2x-138=2^3\cdot3^2\)
\(\Leftrightarrow2x-138=8\cdot9\)
\(\Leftrightarrow2x-138=72\)
\(\Leftrightarrow2x=210\)
\(\Leftrightarrow x=105\)
\(a,2x-138=2^3.3^2\)
\(\Rightarrow2x-138=72\)
\(\Rightarrow2x=72+138\)
\(\Rightarrow2x=210\)
\(\Rightarrow x=210:2\)
\(\Rightarrow x=15\)
Chớt cha nhầm câu a là bằng 105 nha!!!^^
a, 2x - 138 = 8 x 9
2x - 138 = 72
2x= 72 + 138
2x= 210
x= 210 : 2
x= 105
b) 3^x + 25 = 26. 2^2 + 2.1
3^x + 25 = 26. 4 + 2
3^x + 25 = 106
3^x = 106 - 25
3^x = 81
3^x = 3^4
=> x =4
\(3^x+25=26\cdot2^2+2\cdot1\)
\(\Leftrightarrow3^x+25=26\cdot4+2\)
\(\Leftrightarrow3^x+25=206\)
\(\Leftrightarrow3^x=181\)
\(\Leftrightarrow x\in\varnothing\)
2x+138=8x9 3x+25=26x4+2
2x+138=72 3x+25=106
2x=72-138 3x=106-25
2x=-66 3x=81
x=(-66):2=-33 3x=34
x=4
\(b,3^x+25=26.2^2+2.1\)
\(\Rightarrow3^x+25=26.4+2\)
\(\Rightarrow3^x+25=104+2\)
\(\Rightarrow3^x+25=106\)
\(\Rightarrow3^x=106-25\)
\(\Rightarrow3^x=81\)
\(\Rightarrow3^x=3^4\)
\(\Rightarrow x=4\)
\(a.2x-138=2^3.3^2\)
\(\Leftrightarrow2x-138=72\)
\(\Leftrightarrow2x=210\)
\(\Leftrightarrow x=105\)
