10•(3а-b)-17•(2a+b) = 30а -10b - 34 a - 17b = - 4a - 27b= -4×3 - 27×4= -12 -108 = -120
-9t³(2t⁸-3k)+5(4t¹¹-3k) = -18t¹¹+27t³k+20t¹¹-15k = 2t¹¹+27t³k-15k
Cos4x-3cos2x=1
2cos²2x-1-3cos2x-1=0
2cos²2x-3cos2x-2=0
D=9+16=25; √D=5
cos2x=(3+5) /4=2 - |t|≤1
cos2x=-1/2
2x=±2π/3+2πn, n € Z
x=±2π/6+πn, n € Z
<span>(11y+1)⋅(7y−3)=(77y−4)(y+1)
77y</span>²-33y+7y-3=77y²+77y-4y-4
-33y+7y-3=77y-4y-4
-26y-3=73y-4
-26y-73y=-4+3
-99y=-1
y=1/99
4-4x+x²-x²-1.5x=4
-5.5x=0
x=0