Maths. - Ans.fyi 參考答案

Maths.

2010-02-20 6:42 am

1) 2^a=3^b=6^c, find the value of 1/a+1/b.

Ans:________

2) Each of the angles of a triangle expressed in degrees is a perfect square . Find the three angles of the triangle .

Ans: _________
and tell me why~
3)-Y=X^2-5X+5

-Z=X^2-12X+35

-Y=1

I think y=-1,x=4,z=-3

錯?對?

If wrong , tell me why and tell me the answers ,please~

Quick !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

回答 (1)

用戶2053

2010-02-20 8:30 am

✔ 最佳答案

1) 2^a=3^b=6^c
[(2^a)^(1/a)] [(3^b)^(1/b)] = [(6^c)^(1/a)] [(6^c)^(1/b)]
2 * 3 = (6^c)^(1/a + 1/b)
6 = 6 ^ c(1/a + 1/b)
1 = c(1/a + 1/b)
1/c = 1/a + 1/b
Ans:__1/c ______
2)Perfect square less than 180 :

1 4 9 16 25 36 49 64 81 100 121 144 169
180 - 169 = 11 no sol.
180 - 144 = 36 no sol.
180 - 121 = 59 no sol.
180 - 100 = 80 = 16 + 64 , get a sol. : 16 + 64 + 100 = 180
3)
- Y = X^2-5X+5
1 = x^2 - 5x + 5
x^2 - 5x + 4 = 0
(x - 1)(x - 4) = 0
x = 1 or x = 4
-Z=X^2-12X+35
when x = 4 : -Z = 16 - 12*4 + 35 = 3
Z = - 3
when x = 1 : -Z = 1 - 12*1 + 35 = 24
Z = - 24
你 miss 了 y = - 1 , x = 1 , Z = - 24

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