Math 221 Excercises Essay

01 . 24-(19-11) +{(-2)2/2}(-5)+32 =

24-8+(4/2)(-5)+9
24-8+(2)(-5)+9
24-8+-10+9
15

02. (3/5)+(1/8) / (3/4) – (1/7)*(2/3) =

(3/5) + (1/8) * (4/3) – (1/7)*(2/3)
(3/5) + (1/6) – (2/21)
(18/30) + (5/6) – (2/21)
(23/30) – (2/21)
(483/630) – (60/630)
423/630
47/70

03. 20 80 120

MCD = 20
20/20 = 1
80/20 = 4
120/20=6

04. a=2 b= -3

(3a-2)/8 – 6b/a
(32-2)/8 – 6(-3)/2
(9-2)/8 + (18/2)
(7/8) + (18/2)
(7/8) + (72/8)
79/8
9 7/8

05. 2x+4>5x-12

2x-2x+4 > 5x – 2x – 12
4>3x-12
12+4>3x-12+12
16>3x
1/3(16)>3x(1/3)
16/3>x
5 1/3 > x

06.15/25 = 3/x

15/25 = 3/x
(15/25) / 5/5 = 3x
3/5 =3/x
(x/1)(3/5)= (3/x)(x/1)
(3/5)x = 3
(5/3)(3/5)x = 3(5/3)
x=5

07.(6x2+1)(2x-2)

(6x2+1) (x-1)2
(6x3- 6x2 + x – 1)2

08.4x2+8x+3
(2x+3)(2x+1)

09. 4(5x-2y) = 3tx – 5e
20x - 8y = 3tx -5e
-8y – 20x + 20x   = 3tx – 5e + 20x
-8y = 3tx – 5e + 20x
-8y + 5e = 3tx + 20x – 5e + 5e
-8y + 5e = 3tx + 20x
(1/3t)(-8y + 5e) = 20x + (3tx)(1/3t)
(-8y+5e)/3t = 20x + x
(-8y+5e)/3t = 21x
(1/21)((-8y+5e)/3t) = 21x (1/21)
(-8y+5e)/63t = x