求人解答數學難題!!!

q1
設較大的整數為x,較小的為x-1:
x+(x-1)≧37
2x-1≧37
2x≧38
x≧19

q2 唔知條式係咪咁..如果式錯我好樂意計多次:)
a) (x-4)/(2+1)≧x/3
x-4≧x
2x≧4
x≧2

b) (x+1)/(4-2x) + 1/7 <1
(x+1)/(4-2x) < 6/7
7x+7 < 24-12x
19x < 17
x < 17/19

q3
a) 1/a=1/b-1/c
bc=ac-ab
ac+bc=ab
c(a+b)=ab
c=ab/(a+b)


b) d=(3a+b)^2-(3a-b)^2
d=9a^2+6ab+b^2-9a^2+6ab-b^2
d=6ab+6ab
d=12ab
b=d/12a


c) rs=3(r+t)
rs=3r+3t
rs-3r=3t
r(s-3)=3t
r=3t/(s-3)

d) a=b+3(c+b)
a=b+3c+3b
a=4b+3c
4b=a-3c
b= (a-3c)/4


e) 1+3p=q(p+7)
1+3p=pq+7q
3p-pq=7q-1
p(3-q)=7q-1
p=(7q-1)/(3-q)


2011-08-26 02:08:16 補充：
4. 0.35*2*π*1000
=700π
=2199.11米(小數點後兩個位)

5. (30*π*60)/(40π)
=45

6. (2πr)/2=2
πr=2
r=2π
r=0.64 (小數點後兩個位)

7. 20*10*2*(1.05)^3
=463.05

其實我唔肯定e個岩唔岩,但希望幫到你

Q 6.
* is multiplication sign

2 * pi * r/2 + 2r = 2
pi * r + 2r = 2
(pi + 2)r = 2
r = 2/(pi + 2)
r = 2/(3.14159 +2)
r = 2/5.14159
radius = 0.389 m

Q7:
New volume = 463.05 cubic cm (please specify the unit)

Q3 e: It is correct