<span>cos(π/5)*cos(2π/5)</span><span><span>=<span><span>sin(π/5)*cos(π/5)*cos(2π/5)/</span><span>sin(π/5)</span></span></span><span>=<span><span>sin(2π/5)*cos(2π/5)/</span><span>2sin(π/5)</span></span></span><span>=<span><span>sin(4π/5)/</span><span>4sin(π/5)</span></span></span><span>=<span>1/4</span></span></span>
1) ln(√2x) - 1
y! = 1/√2x * [1/2*(√2x)*2] = 1√2x
2) ln(√(2x - 1)
y! = [1/(√(2x - 1)] * [1/2*√(2x)]*2 = 1/√(2x)*√(2x) - 1)
10х-20+19=5х+25х-1-5х
10х-5х-25х+5х=-1+20-19
-15х=0
х=0
Log8x^2-23x+15 (2x-2)≤0
( в условии пропущен х возле 23)