問數 (32000=100n^2+4000n) 20點

32000=100n^2+4000n
32000=100(n^2+40n)
320=n^2+40n
n^2+40n-320=0
n={-40±√[(40)^2-4(1)(-320)]}/2(1)
n=[-20±√(1600+1280)]/2
n=6.83or n=-46.83

If
320000=100n^2+4000n
3200=n^2+40n
n^2+40n-3200=0
(n-40)(n+80)=0
n=40 or n=-80


所以你應該少了一個零

40*-80
=-3200

怎麼那麼多人都算錯了呢!?

320000 = 100n^2+4000n 幫你加返個零

320000=100n^2+4000n <~~全部除100
320=n^2+40n <~~全部放係同一邊
0 = n^2+40n-320 <~~要用公式..如果你有學過既話

n -40 用n^2 同 -320 交叉相乘...
n +80 個答案要等於 40n
----------------------
-40n + 80n = 40n

(n- 40)(n+80)=0

n=40 or n= -80

1)32000=100n^2+4000n

32000=100*40^2+4000*40

32000=160000+160000

32000=320000????????????????????????
你係咪少左個0?

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2)32000=100n^2+4000n
320=n^2+40n
n^2+40n-320=0
(n- 40)(n+80)=0
(n- 40)=0 or (n+80)=0
n=40 or n= -80

32000=100n^2+4000n
320=n^2+40n
n^2+40n-320=0
(n- 40)(n+80)=0
(n- 40)=0 or (n+80)=0
n=40 or n= -80