請列式!!!!!!!!
1.(a)Expand (a+2b)^2
(b)Hence expand (a+2b+4c)^2
(answer= a^2+4b^2+16c^2+4ab+8ac+16bc )
2.If (x+1)^2+P(x+1)≡x^2+Q,find the value of P and Q
(P=-2 Q=-1)
3.Simplify ("──"represent fraction )
1 - 2x
───────
x - 1
───
x
(Answer: x^2+1
────
x^2-1
4.On a particular day ,the high tide was 1.8m above and the low tide was 1.6m
below a mark on a coastal wall .Both measurements are correct to 2 signifisant
figures.Find the lower limit for the difference of heights between the high and the low
tides
(answer=3.3)
5.The CTU(Central Processing Unit )of Jerry ' s computer can complete 4 x 10^9
calculations each second.
(a) How long does it take to complete 1 calculation?
(answer=2.5x10^-10)
6.Simon wants to sketch the picture of a ship with an actual length of 290 m and
actual width of 190m .He is using a piece of drawing paper size 17cm x 25cm.
What is the maximum posssible scale of the drawing?
(answer=1:11600)
7.Terry bought 2 model car that have a scale of 1:35.It was found that the difference
on length of the models is 3 cm . If the actual length of the smaller car is 2.5m, what is the actual length of the large car.
(answer=3.55 m)
8.A car finish a job in 6 days alon while B can finish the same job in 12 days aloe.
If A and B work together ,how many days do they need to finish the job?
(answer=4 days)
**盡量答!!請列詳細一點!thank a lot!!
(急!)f2 數學問題!20分!(內附答案,but要列式!)
2010-01-02 3:31 am
回答 (1)
2010-01-02 4:50 pm
✔ 最佳答案
1a) (a+2b)^2=a^2+2(a)(2b)+(2b)^2=a^2+4ab+4b^2b) (a+2b+4c)^2=(a+2b)^2+2(a+2b)(4c)+(4c)^2=a^2+4ab+4b^2+8ac+16bc+16c^2
=a^2+4b^2+16c^2+4ab+8ac+16bc
2) (x+1)^2+P(x+1)=x^2+Q
x^2+2x+1+Px+P=x^2+Q
(2+P)x+(1+P)=Q
So,2+P=0 ie P=-2
Q=1+P=1+(-2)=-1
3)answer is not correct
(1-2x)/((x-1)/x)=(x-2x^2)/(x-1)
4)the lower limit for the difference of heights between the high and the low tides
=(1.8-0.05)+(1.6-0.05)=3.3
5(a) the time required=1/(4 x 10^9)=(4 x 10^9)^(-1)=2.5x10^(-10)s
(6)answer is not correct
if we use the side of paper with 25cm to draw the length of ship,
the scale=1:1160
7) length of the smaller car=2.5/35=1/14m=50/7cm
length of the large car=50/7+3=71/7cm
actual length of the large car=71/7x35=355cm=3.55m
8)let the job is a
speed of A=a/6
speed of B=a/12
speed of A+speed of B=a/4
the time required=a/(a/4)=4days
收錄日期: 2021-04-13 17:00:59
原文連結 [永久失效]:
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