№3 2ˣ⁻²(2²+2+1)=5ˣ⁻²(5²+5+1) 2ˣ⁻²/5ˣ⁻²=31/7 (0.4)ˣ⁻²=31/7
x-2=log0.4 (31/7) x=log0.4(31/7)+2
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№4 2^(√x)=z z>0 x≥0
0.5*16*z²-35z+12=0
8z²-35z+12=0 D=35²-4*8*12=1225-384=841 √D=29
z1=1/16[35-29]=3/8 2^√x=3/8 √x=log2 (3/8)<0 отбрасываем<br> z2=1/16[35+29]=4 2^√x=2² √x=2 x=4