А)16х^2+8х=0
8х(2х+1)=0
2х+1=0. 8х=0
2х= 1. х2=0
х1= -1/2
b)36-144х^2=0
144х^2=36
х^2=36/144
х^2= 1/4
х= +- 1/2
c) 5x^2+7x-6=0
D=7^2-4×5÷(-6)=49+120=169
X1= -7+13/2×5=6/10=3/5
X2= -7-13/2×5= -20/10= -2
125+a³-a³+125=250
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Cos40+cos10 + cos30+cos20= 2cos((40+10)/2)*cos((40-10)/2)+ 2cos((30+20)/2)*cos((30-20)/2)=2cos25*cos15+2cos25*cos5=2cos25(cos15+cos5)=2cos25(2cos((15+5)/2)*cos((15-5)/2))=2cos25(2cos10*cos5)
<span>1)0,125×0,25×0,5= 1/8* 1/4*1/2=1/64 = 2</span>⁻⁶<span>
2)0,4^5×0,16 = 0,4</span>⁵<span> * 0,4</span>² = 0,4⁷
⁴√(3/64) * ⁴√(27/4) = ⁴√(3/4³ * 3³/4) = ⁴√(3/4)⁴ = 3/4 = 0,75