8a²b+(-5a²b+4b²)+(a²b-5b²+2)=8a²b-5a²b+4b²+a²b-5b²+2=4a²b-b²+2
<span>5sin3x - 9sin x = 0</span>
5(3sinx - 4sin^3 x) - 9sinx = 0
15sinx - 20sin^3 x - 9 sinx = 0
6sinx - 20sin^3 x = 0
2sinx (3 -10sin^2 x) = 0
a) 2sinx = 0
sinx = 0
x1= πn
б) 3 - 10sin^2 x = 0
10sin^2x = 3
sin^2x = 3/10
sinx = +-√(3/10)
sinx = √(3/10)
x2 = (-1)^n * arcsin(3/10)+πn
sinx = -√(3/10)
x3 = (-1)^(n+1) * arcsin(3/10)+πn
файл
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1)4х(х-3)-х(4х+3)=45
4х2-12х-4х2-3х=45
4х2-4х2-12х-3х=45
15х=45
х=45:15
х=3
2)2х(2х-4)-х(4х-6)=19
4х2-8х-4х2+6х=19
-2х=19
х=19:(-2)
х=-9,5
3)3х(2х+5)-6х(х-5)=90
6х2+15х-6х2+30х=90
15х+30х=90
45х=90
х=90:45
х=2