7*(-3/7) - 3*5/6= -3 - 5/2= -6/2-5/2= -5 1/2
Cos 2a + sinˇ2 a = cosˇ2a -sinˇ2a + sinˇ2a = cosˇ2a
sin40/2cos20 = 2.sin20.cos20/2.cos20 = sin20
sin100/2.cos50 = sin (2.50)/2.cos50 = 2.sin50.cos50/2.cos50 = sin50
2*(1,5х)-1/3х=24
3х-1/3х=24
2 2/3х= 24
х= 24: 2 2/3 = 24/1*3/8 =6*3/1*2=3*3
х=9
|5 - 2x| ≤ 1
Данное неравенство равносильно двойному неравенству:
-1 ≤ 5 - 2x ≤ 1
-1 - 5 ≤ -2x ≤ 1 - 5
-6 ≤ -2x ≤ -4
2 ≤ x ≤ 3
Ответ: x ∈ [2; 3]