1-2sin²x+5sinx+2=0
sinx=a
2a²-5a-3=0
D=25+24=49
a1=(5-7)/4=-1/2⇒sinx=-1/2⇒x=(-1)^(n+1)*π/6+πn,n∈z
a2=(5+7)/4=3⇒sinx=3>1 нет решения
1)
а²b²*(a²+3ab-b²)=
= a⁴b²+3a³b³-a²b⁴
-m(m-2) +5m²(1-3m)=
=-m²+2m+5m²-15m³=
=4m²+2m-15m³
2)
6(5x-4)-3(3x-2)=5
30x-24-(9x-6)=5
30x-24-9x+6=5
30x-9x=5+24-6
21x= 23
x=23/21
x= 1 2/21
Проверим:
6(5 * 23/21 -4)- 3(3* 23/21 -2)=5
6 ( 115/21 - 84/21 ) - 3( 23/7 - 14/7 )=5
6 * ( 31/21) - 3 * (9/7) =5
62/7 - 27/7 =5
35/7=5
5=5
3х+1/5х=6
3 1/5х=6
3.2х=6
Х=6:3.2
Х=60:32
Х=60/32
Х=30/16
Х=15/8
Х=1 7/8
2x³ - 16 = 0
2x³ = 16
x³ = 8
x = ∛8
x = 2