1. а) xy(x +y) -2(x +y) = (x+y)(xy-2)
б) a^3 +5^3=(a +5)(a² -5a+25)
2. a) (c +4)(c -1) -c² = c² -c +4c -4 -c² = 3c -4
b) выносим общий множитель (x -4) за скобки
(x -4)(5 -x -4)= (x -4)(1 -x) = x -x² -4 +4x =5x -x² -4
в) (3 -4x)(16x) +64x² -48x +9 =48x -64x² +64x² -48x +9 =9
3. y -100y^3 =y(1 -10²y²) = y(1 -10y)(1 +10y)
значок ^ обозначает в степени
5x-7y
<span>а) При x = 3/5 , y= - 4/7
</span>5*3/5-7*(-4/7)=
=3-(-4)=3+4=7
5*3/5=5/1*3/5=3/1=3
7*(-4/7)=7/1*(-4/7)=-4/1=-4
<span>б) при x = - 0,8 , y = 0,6
</span>5*(-0,8)-7*0,6=
=-4-4,2=-8,2
5
<u>0,8
</u>40
<u>0
</u>-4,0
7
<u>*0,6
</u> 42
<u> 0
</u> 4,2
2.
а) 7/39 - (1/13 - 2/3) и 7/39 + ( 2/3 - 1/3)
10/13 > 20/39
1/13 - 2/3=3/39-26/39=- 23/39
7/39-(-23/39)=7/39+23/39=30/39=10/13
2/3 - 1/3=1/3
7/39+1/3=7/39+13/39=20/39
б) 3/5 + 1/8:5/4 и (3/5 + 1.8) : 5.4
7/10 > 4/9
1/8:5/4=1/8*4/5=1/2*1/5=1/10
3/5+1/10=6/10+1/10=7/10
3/5 + 1.8=3/5+1 4/5=3/5+9/5=12/5=2 2/5
2 2/5:5,4=2 2/5:5 2/5=12/5:27/5=12/5*5/27=4/1*1/9=4/9
Х² -6х +9 = х² + 4х - 5х - 20
- 6х - 4х +5х = - 20 - 9
- 5х = - 29
х = 5,8
1) (x+101)/(x+7) = 13
x + 101 = 13 x + 91
12x = 10
<span>x = 5/6
</span>2) 5 ( 8x+4 ) + 1> 26x + 147
40 x + 20 + 1 - 26x >147
14x > 147 - 20 - 1
x>9
3) -22 = х - x^2
x^2 - x- 22 = 0
D = 89
x1 =
x2 =
4) (x-6)(-x-10) = 58
-x^2 - 4x + 2 = 0
x^2 + 4x - 2 = 0
D = 24
x1 = (-4-2√6)/2 = -2 -√6
x2 = -2 + <span>√6</span>
147*85+53*60+147*15+53*40=
147(85+15)+53(60+40)=
147*100+53*100=
100(147+53)=100*200=20000