А)3 5/8 × 1 7/9 = 29/8 × 16/9 = 58/9 = 6 4/96 4/9 × 21/58 = 58/9 × 21/58 = 7/3 = 2 1/3ответ 2 1/3б)2/9 + 5/6 = (2 × 2 + 5 × 3)/18 = 4/18 + 15/18 = 19/18 = 1 1/181 1/18 × 36 = 19/18 × 36 = 38ответ 38в)4 - 7/8 =(4 × 8 - 7 × 1)/8 = 32/8 - 7/8 = 25/8 = 3 1/83 + 1/5 =3 1/53 1/8 × 3 1/5 = 25/8 × 16/5 = 10ответ 10
2x-11y-5x-12y+3x-17y= -40y. Ответ: -40y.
sin(a+b)*sin(a-b) = (sina*cosb + cosa*sinb)*(sina*cosb - cosa*sinb) =