F.4 2題math唔識做... 高手 請教!!!

1.

Let the smaller positive even number by n.

Thus the greater positive even number = n + 2


The product of the two even number:

n(n + 2) = 528

n2 + 2n - 528 = 0

(n - 22)(n + 24) = 0

n = 22 ooro n = -24 (rejected)

n + 2 = 24


Ans: The two positive even numbers are 22 and 24.

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2.
Let w m be the width of the path.

(20+2w)(16+2w) - 20*16 = 352

320 + 72w + 4w2 - 320 = 352

4w2 + 72w - 352 = 0

w2 + 18w - 88 = 0

(w - 4)(w + 22) = 0

w = 4 ooro w = -22 (rejected)

Ans: The width of the path is 4 m.
=

1. The product of two consecutive positive even numbers is 528.find the two number.

let the smaller number be X, then the other be X 1
(X)(X+1)=528
3X=528
X=176

2.let the width of the path be X,then
(20+2X)(16+2X)=352+(20)(16)
320+32X+40X+4X^2=672
4X^2+72X-352=0
(X-4)(X 22)=0
X=4 or -22
the width of the path is 4 or -22

2008-10-21 21:52:43 補充：
sorry
1. The product of two consecutive positive even numbers is 528.find the two number.

let the smaller number be X, then the other be X 1
(X)(X+2)=528
4X=528
X=132