(3/2-2/3)х=30
5х/6=30
х=180/5
<span>х=36</span>
Х²-6х-1=6+х²+х
х²-6х-1-6-х²-х=0
-7х-7=0
х=-1
проверка
(-1)²-6*(-1)-1=6+(-1)²-1
1+6-1=6+1-1
6=6
X²+2x-3=0 a=1; b=2; c=-3
D= b²-4ac = 4-4·(-3) = 4+12 = 16 = 4²
x1 = (-b-√D)÷2a = (-2-4)÷(2·1) = -6÷2 = -3
x2 = (-b+√D)÷2a = (-2+4)÷(2·1) = 2÷2 = 1
6.
[(a-b)(a+b)/2a²] * [a/(2(a+b))]=(a+b)/(4a)
(√2+√98)/(4√2)=(√2+√2*√49)/(4√2)=(√2+7√2)/(4√2)=
=(8√2)/(4√2)=2
6cos²x+5cosx-4=0 U sinx≥0
cosx=a
6a²+5a-4=0
D=25+96=121
a1=(-5-11)/12=-4/3⇒cosx=-4/3 нет решения
a2=(-5+11)/12=1/2⇒cosx=1/2⇒x=+_π/3+2πn
sinx=0⇒x=πn
x={-5π/3;-π}∈(-2π;-π/2)