1) (1.68:1.6-2.1)(-1 2/3)-2 1/6 =
= (1,05-2.1)(-1 2/3) - 2 1/6 =
= -1,05*(-1 2/3) - 2 1/6 =
= 1 1/20 * 1 2/3 - 2 1/6 =
= 21/20 * 5/3 - 13/6 =
= 7/4 - 13/6 = 21/12 - 26/12 = -5/12
2) (√16)³ - 51⁰ - 3² * 3⁻⁴ - 2:2⁻³ =
= 4³ - 1 - 3⁻² - 1:2⁻² =
= 64 - 1 - 1/9 - 1/4 =
= 63 - 4/36 - 9/36 =
= 63 - (4/36 + 9/36) =
= 63 - 11/36 =
= 62 25/36
Если 0 < a < 90, то sin a > 0; cos a > 0; tg a > 0
cos^2 a = 1 - sin^2 a = 1 - 9/25 = 16/25
cos a = 4/5
tg a = sin a / cos a = (3/5) / (4/5) = 3/4
tg a + cos^2 a = 3/4 + 16/25 = (75 + 48)/(4*25) = 123/100 = 1,23
ОДЗ: x>-8
log₇[(x+8)/11]=log₇2
(x+8)/11=2
x+8=22
x=22-8=14