9,9^2 = (10 - 0,1)^2 = 10^2 - 2*10*0,1 + 0,1^2 =
= 100 - 2 + 0,01 = 98 + 0,01 = 98,01
<span>6sin^2x+4sinxcosx+4cos^2x=3
</span>6sin^2x+4sinxcosx+4cos^2x=3(sin^2x+cos^2x)
3sin^2x+4sinxcosx+cos^2x=0
разделим на cos^2x
3tg^2x+4tgх+1=0
Примем tgх=у
3у^2+4y+1=0
(y+1)(3y+1)=0
У1=-1 У2=-1/3
tgx1=-1
x1=5пи/4
tgx2=-1/3
х2=13пи/12
(b+5)^2+2 (b+5)(4-b)+(4-b)^2=b^2+25+10b+2 (4b-b^2+20-5b)+16+b^2-8b=2b^2+41+2b+8b-2b^2+40-10b=81
<span><span>1) √(21)</span></span><span> = </span><span>4,58257569496</span>
<span><span> √(14)</span></span><span> = </span><span>3,74165738677</span>
<span><span> √(6)</span></span><span> = </span><span>2,44948974278</span>