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標題:

數 - (49) 2 + 4 = 22

發問:

• 一手50指
• 請教數學題_1@1@
• 2010歐聯決賽幾月幾日,什麼時間開波@1@

• 一手50指
• 請教數學題_1@1@
• 2010歐聯決賽幾月幾日,什麼時間開波@1@

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2 + 4 = 22 Find 2 You don't know ? It should be : a + 4 = aa a + 4 = a ^ 2 Find a

最佳解答:

Solve a + 4 = a ^ 2 a^2 - a - 4 = 0 a^2- 2(0.5)a-4 = 0 (a^2 - 2(0.5)a+0.25)-0.25-4=0 (a-0.5)^2 -4.25 =0 (a-0.5+√4.25)(a-0.5-√4.25)=0 a=0.5+√4.25 =2.56(3 sig. fig.) OR a=0.5-√4.25 = -1.56 ( 3 sig. fig)

其他解答:

- (49) 2 + 4 = 22 - 2(7x7) + 2x2 = 2(3x3) + 2x2 or -2(-7x-7) + (-2x-2) = 2(-3x-3) + (-2x-2) a = 3 or a = -3