-3x • (x - 4) = -3x • x - 3x • (-4) = -3x² + 12x
5x²y • (x² - y) = 5x²yx² - 5x²y • y = 5x⁴y - 5x²y²
(7x - 2) • (x - 5) = 7x² - 35x - 2x + 10 = 7x² - 37x + 10
8/9-5/6=16/18-15/18=1/18
9×2 11/15=9×41/15=369/15=24 9/15=24 3/5
Cos(α-β) -2sinα sinβ= cosα cosβ + sinα sinβ - 2sinα sinβ =
=cosα cosβ - sinα sinβ = cos(α+β)
При α=46° и β=74°
cos(46°+74°)=cos120°=cos(90°+30°)= -sin30° = -1/2
Ответ: -1/2