X²-7(x-4)=28
x²-7x+28-28=0
x²-7x=0
x(x-7)=0
x=0 или x-7=0
x=7
<span>2,18* 10в 6 степени..............................................................................................</span>
-100m²+20m-1 = - (100m²-20m+1) = -(10m-1)²
при m = 0.1
-(10 * 0.1 - 1)² = -(1-1)² = 0
1
сtg3x-ctgx=0
sin(3x-x)/sin3x*sinx=0
sin2x=0 U sin3x*sinx≠0
2x=πn⇒x=πn/2,n∈z U x≠πk,k∈z U x≠πm/3,m∈z
x=πn/2,n∈z U n≠2m/3,m∈z
3
sin(2x+4x)/cos2xcos4x=sin(5x+x)/cos5xcosx
sin6x/cos2xcos4x-sin6x/cos5xcosx=0
sin6x(cos5xcosx-cos2xcos4x)/cosxcos2xcos4xcos5x=0
cosxcos2xcos4xcos5x≠0
sin6x=0⇒x=πn/6,n∈z
cos5xcosx-cos2xcos4x=0
1/2*cos4x+1/2*cos6x-1/2*cos2x-1/2*cos6x=0
1/2*cos4x-1/2*cos2x=0
-1/2*2sinxsin3x=0
sinx=0⇒x=πk,k∈z
sin3x=0⇒x=πm/3,m∈z
1) x1=0.25 x2=-0.5
2) x1=0 x2=8
3) x1=0 x2=16
4) x1=-3 x2=-1+1i x3=-1-1i x4=1