36+(44+19)=99
(4*9)÷6=6
(64÷8)+46=54
(11+25)÷(15-6)=4
(6*9)-37=17
(31-25)*(5+3)=48
1000х+0,01у=1000*0,2346+0,01*26540=234,6+265,4=500
Cos²a = 1 - sin²a= 1 - 25/169 = 144/169;
cos a = - 12/13;
sin2a = 2sinacosa = 2 * 5/13 * (- 12/13) = -120/169;
cos2a = cos²a - sin ²a = 144/169 - 25/169 = 119/169
tg2a = sin2a/cos2a
tg2a = - 120/169 / 119/169= - 120/119
(8/25 * 15 + 1/20 * 4) * 3/5 = 3
1) 8/25 * 15 = 24/5 = 4 4/5
2) 1/20 * 4 = 4/20 = 1/5
3) 4 4/5 + 1/5 = 4 5/5 = 5
4) 5 * 3/5 = 3