(k-1)x²+(k+4)x +k+7=0
a=k-1,b=k+4, c=k+7
D=b²-4ac, x1=x2⇔D=0
(k+4)²-4.(k-1)(k+7)=0
k²+8k+16-4(k²+6k-7)=0
k²+8k+16-4k²-24k+28=0
-3k²-16k+44=0
3k²+16k-44=0,D=16²-4.3.(-44)=256+528=784,√D=√784=28
k1=(-16+28)/6=12/6=2
k2=(-16-28)/6=-44/6=-22/3=-7 1/3
А1. а) -0,01х^2х•10х^4=-0,1х^7
б) 2а^2b^5•8a^3b^2a=16a^6b^7
A2. a) (10x^4y^3)^2•(0,8x)^2•y^9 =
= 100x^8y^6•0,64x^2•y^9 =
= 64x^10y^17
б) (-5а^3b^4)^2•(-0,2ab^2)^2 =
= 25a^6b^8•0,04a^2b^4 =
= a^8b^12
в) (10а^3)^5•(-2а^2)^2 =
= 100000а^15•4а^4=400000а^19
В1. а) 121х^12у^4=(11х^6у^2)^2
б) 0,09а^6b^2=(0,3a^3b)^2
B2. Сторону квадрата надо изменить в 6 раз.
Сosa-cosb=-2sin(a-b)/2*sin(a+b)/2
cos3a-cos5a=2sinasin4a
<em><span>3(1-(-</span></em><em><span>2)(</span></em><em><span>5 степени</span></em><em><span>):(делится на)</span></em><em><span>1+2</span></em><em><span>=</span></em><em><span>3×3</span></em><em><span>3(поделить на 3</span></em><em><span>)=</span></em><em><span>33</span></em><span />
X² - 64 = 0
x² = 64
x = 8
x = -8
Ответ: -8; 8
(x+5)² - (x-1)² = 48
x² + 10x + 25 - x² + 2x - 1 = 48
12x = 48 - 24
12x = 24
x = 2
Ответ: 2