4.sinπ/6+3tg²π/4+cotgπ/4+2.cosπ/3=4.0,5+3.1²+1+2+0,5=
=2+3+1+0,5=6,5
(sinπ/6=cosπ/3)=0,5 , tgπ/4=cotgπ/4=1)
Решить уравнение:
х^2(<span>х+1)-(х+2)(2х-3)=х^2(х-1)
x^3 + x - 3x + 3 x - 4x + 6 = x^3 -x
</span><span>x^3 + x - 4x + 6 = x^3 -x
</span>x^3 + x - 4x - <span>x^3 + x</span> = - 6
x - 4x <span>+ x = - 6
</span>2x - 4x = - 6
-2x = - 6
x = - 6 / - 2
x = 3
Log 5^35 - log 5^7 = log(5^35 / 5^7) = log(5^(35 - 7) ) = log 5^28 = 28log 5
Второй вариант решения.
log 5^35 - log 5^7 = 35log 5 - 7log 5 = (35 - 7) * log 5 = 28log 5
Ответ. 28log 5
Числа Х и у
Система уравнений
Х + у = 53( Х - у )
Х^2 - у^2 = 212
Решение
Х + у = 53х - 53у
54у = 52х
у = ( 52/54 )Х
у = ( 26/27 )Х
Х^2 - ( ( 26/27)х )^2 = 212
Х^2 - ( 676/729 )х^2 = 212
729х^2 - 676х^2 = 212 • 729
53х^2 = 154548
Х^2 = 2916
Х1 = 54
Х2 = - 54 ( < 0 )
у = ( 26/27 )Х
у = 26/27 • 54
у = 52
52 < 54
Ответ 52