4sinx-cosx=2cosx-sinx
4sinx+sinx=2cosx+cosx
5sinx=3cosx разделим обе части на cosx
5*sinx/cosx=3*cosx/cosx
5tgx=3
tgx=3/5=0,6
1)3*(5х+8+х)=3*5х+3*8+3*х=15х+24+3х=18х+24;
2)(4х+8)*7=7*4х+7*8=28х+56;
3)5(10у+7)=5*10у+5*7=50у+35;
4)21х*(7+4х)=21х*7+21х*4х=147х+84х^;
5) 32х-12=55
32х=55+12
32х=67
х=67:32
х=2,09375
<span>1)
2x</span>²<span>+ 24xy +72y</span>² = 2 ·(х²+12ху+36у²) = 2·(х+6у)² = 2·(х+6у)(х+6у)
<span>2)
-8a</span>⁵<span> +8а</span>³<span> - 2а = -2а</span>·(4а⁴-4a²+1) = -2a·(2a²-1)² = -2a·(2a²-1)(2a²-1)
<span>3)
5a</span>³<span> - 40b</span>⁶ = 5a³ ·(1-8b³) = 5a³ ·(1³ - (2b)³) = 5a³·(1-2b)(1+2b+4b²)
<span>4)
8а</span>³<span> -аb - a</span>²<span>b + а</span>² = a·(8a²-b-ab+a)
Х:5-3=х:2
2x-30=5x
2x-5x=30
-3x=30
x=-10
Смотри решение во вложении