1).25а^3 - аb^2 = a(25a^2 - b^2) = a(5a-b)(5a+b)
2).-3х^2 - 12х-12 = -3(x^2 + 4x + 4) = -3(x+2)^2
3).3ab-15a+12b-60 = 3a(b-5) + 12(b-5) = (b-5)(3a+12)
4).a^4 - 625
= a^4 - 5^4 = (a^2)^2 - (5^2)^2 = (a^2 - 5^2)(a^2+5^2)
1) = (m-3)/2m - (m-4)(m+4)/m * 1/3(m+4) = (m-3)/2m - (m-4)(m+4)/3m(m+4) =
(m-3)/2m - (m-4)/3m = ( 3(m-3) - 2(m-4) ) / 6m = (3m - 9 - 2m + 8)/6m = (m-1)/6m
2) 2x^2 - 14x < (1+5x)(x-2)
2x^2 - 14x < x - 2 + 5x^2 - 10x
2x^2 - 14x - x + 2 + 5x^2 + 10x < 0
-3x^2 - 5x + 2 < 0
3x^2 + 5x - 2 > 0
1. y=3x^2 + 5x - 2
2. y = 0
D = 25 - 4*3*(-2)=25+24=49
x1=1/3
x2=-2
Ответ: (-бесконечность; -2) и (1/3; +бесконечность)
15cos2t+8sint=9 1<t<3
15*(1-2sin^2t)+8sint=9
15-30sin^2t+8sint=9
sin^2t=x
15-30x^2+8x=9
-30x^2+8x+15-9=0
-30x^2+8x+6=0
-15x^2+4x+3=0
15x^2-4x-3=0
D=16+12*15=14^2
x=(4+14)/30=18/30
x=(4-14)/30=-1/3
sin^2t=-1/3 ne zadovilna
sin^2t=18/30
sint=+-sqrt(18/30)
t=(-1)^n*arcsin(+-sqrt(18/30))+2pin;nEz;