<span>1) x(lg5-1)=lg(2^x+1)-lg6
xlg5-x=lg(2^x/6+1/6)
lg5^x-lg10^x=lg(2^x/6+1/6)
lg(5^x/10^x)=lg(2^x/6+1/6)
5^x/5^x*2^x=2^x/6+1/6 5^x</span>≠0 сократим и умножим на 6
6/2^x=2^x+1
2^x=a a>0
6/a=a+1
6=a^2+a
a^2+a-6=0
a1=-3 искл посторонний корень a2=2
2^x=2
x=1
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17.6×17.6=309.76
2.4×2.4=5.76
309.76-5.76=304
10³=1000
304÷1000=38/125
сначала умножаем на множитель ![\sqrt{5+\sqrt{11}}](https://tex.z-dn.net/?f=%5Csqrt%7B5%2B%5Csqrt%7B11%7D%7D)
![\frac{7\sqrt{5+\sqrt{11}}}{\sqrt{5-\sqrt{11}} \sqrt{5+\sqrt{11}}}=\frac{7\sqrt{5+\sqrt{11}}}{5-\sqrt{11}}](https://tex.z-dn.net/?f=%5Cfrac%7B7%5Csqrt%7B5%2B%5Csqrt%7B11%7D%7D%7D%7B%5Csqrt%7B5-%5Csqrt%7B11%7D%7D%20%5Csqrt%7B5%2B%5Csqrt%7B11%7D%7D%7D%3D%5Cfrac%7B7%5Csqrt%7B5%2B%5Csqrt%7B11%7D%7D%7D%7B5-%5Csqrt%7B11%7D%7D)
потом снова умножаем на 5+√11
![\frac{7(5+\sqrt{11})\sqrt{5+\sqrt{11}}}{(5-\sqrt{11})(5+\sqrt{11})}=\frac{7(5+\sqrt{11})\sqrt{5+\sqrt{11}}}{25-11}=\frac{(5+\sqrt{11})\sqrt{5+\sqrt{11}}}{2}](https://tex.z-dn.net/?f=%5Cfrac%7B7%285%2B%5Csqrt%7B11%7D%29%5Csqrt%7B5%2B%5Csqrt%7B11%7D%7D%7D%7B%285-%5Csqrt%7B11%7D%29%285%2B%5Csqrt%7B11%7D%29%7D%3D%5Cfrac%7B7%285%2B%5Csqrt%7B11%7D%29%5Csqrt%7B5%2B%5Csqrt%7B11%7D%7D%7D%7B25-11%7D%3D%5Cfrac%7B%285%2B%5Csqrt%7B11%7D%29%5Csqrt%7B5%2B%5Csqrt%7B11%7D%7D%7D%7B2%7D)