2^(x-1)+2^(x-2)+2^(x-3)=448
2^x *2⁻¹+2^x*2⁻²+2^x*2⁻³=448
2^x*(1/2)+2^x*(1/4)+2^x*(1/8)=448
2^x*(1/2+1/2+1/8)=448
2^x*(7/8)=448
2^x=448:(7/8)
2^x=512
2^x=2⁹
<u>x=9</u>
Извини, но текст плохо видно(
Раскроем скобки x^2-4x+4=x^2-18x+81
16x=77
x=5,5
<span>2х² · 7ху² - 4х²у (-ху) - 3х · 5х²у² = 14 х</span>³<span>у</span>²<span> - 4х</span>³<span>у</span>²<span> - 15х</span>³<span>у</span>²<span> = -5х</span>³<span>у</span>²
-5х³у² х = -3, у=5
-5 . (-3)³ . 5² = 3375
(-3)³ = -27
5² = 25
-5 . (-27) = 135
135 . 25 = 3375