標題:
二次方程..明天考試,感謝!幫幫忙!
下面有d數,我知簡單果d點計,但係呢種類型唔識..解釋長盡d.steps 1. 如果8(x-3)=3x-x^2, 求x-1的值 2. 如果(x-2)(x-3)=0, (x+1)(x+2)=? 3. 3^x=36-3^x-1 x=? 上述幾種題型唔係好清楚,希望大家解答同解釋一下!!!
最佳解答:
1) 8(x-3)=3x-x^2 8x-24=3x-x^2 x^2+8x-3x-24 x^2+5x-24=0 (x-3)(x+8)=0 so x-3=0 or x+8=0 x=3 or x=-8 if x=3 then x-1=3-1=2 if x=-8 then x-1=-8-1=-9 2)(x-2)(x-3)=0 so x-2=0 or x-3=0 x=2 or x=3 if x=2 then (x+1)(x+2)=(2+1)(2+2)=3*4=12 if x=3 then (x+1)(x+2)=(3+1)(3+2)=4*5=20 3) 3^x=36-3^x-1 3^x+3^x-1=36 3^x(1+1/3)=36 3^x(4/3)=36 3^x=36(3/4) 3^x=27 3^x=3^4<-----27=3的4次方 x=4 2009-01-19 18:50:30 補充： sorry 第三題的答案係3 因為3^3=27
其他解答:
1) 8(x-3)=3x-x^2 8x-24=3x-x^2 x^2+8x-3x-24 x^2+5x-24=0 (x-3)(x+8)=0 so x-3=0 or x+8=0 x=3 or x=-8 if x=3 then x-1=3-1=2 if x=-8 then x-1=-8-1=-9 2)(x-2)(x-3)=0 so x-2=0 or x-3=0 x=2 or x=3 if x=2 then (x+1)(x+2)=(2+1)(2+2)=3*4=12 if x=3 then (x+1)(x+2)=(3+1)(3+2)=4*5=20 3) 3^x=36-3^x-1 3^x+3^x-1=36 3^x(1+1/3)=36 3^x(4/3)=36 3^x=36(3/4) 3^x=27 3^x=3^4<-----27=3的4次方 x=4|||||1 8(x-3)=3x-x^2 x^2-3x+8x-24=0 x^2+5x-24=0 (x+8)(x-3)=0 x=3 or -8 2 (x-2)(x-3)=0 x=2 or 3 when x=2 (x+1)(x+2)=12 when x=3 (x+1)(x+2)=20 3^x=36-3^(x-1) 3^(x-1)+3^x=36 3^(x-1)(1+3)=36 3^(x-1)=9 x=3
二次方程..明天考試,感謝!幫幫忙!
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發問:下面有d數,我知簡單果d點計,但係呢種類型唔識..解釋長盡d.steps 1. 如果8(x-3)=3x-x^2, 求x-1的值 2. 如果(x-2)(x-3)=0, (x+1)(x+2)=? 3. 3^x=36-3^x-1 x=? 上述幾種題型唔係好清楚,希望大家解答同解釋一下!!!
最佳解答:
1) 8(x-3)=3x-x^2 8x-24=3x-x^2 x^2+8x-3x-24 x^2+5x-24=0 (x-3)(x+8)=0 so x-3=0 or x+8=0 x=3 or x=-8 if x=3 then x-1=3-1=2 if x=-8 then x-1=-8-1=-9 2)(x-2)(x-3)=0 so x-2=0 or x-3=0 x=2 or x=3 if x=2 then (x+1)(x+2)=(2+1)(2+2)=3*4=12 if x=3 then (x+1)(x+2)=(3+1)(3+2)=4*5=20 3) 3^x=36-3^x-1 3^x+3^x-1=36 3^x(1+1/3)=36 3^x(4/3)=36 3^x=36(3/4) 3^x=27 3^x=3^4<-----27=3的4次方 x=4 2009-01-19 18:50:30 補充： sorry 第三題的答案係3 因為3^3=27
其他解答:
1) 8(x-3)=3x-x^2 8x-24=3x-x^2 x^2+8x-3x-24 x^2+5x-24=0 (x-3)(x+8)=0 so x-3=0 or x+8=0 x=3 or x=-8 if x=3 then x-1=3-1=2 if x=-8 then x-1=-8-1=-9 2)(x-2)(x-3)=0 so x-2=0 or x-3=0 x=2 or x=3 if x=2 then (x+1)(x+2)=(2+1)(2+2)=3*4=12 if x=3 then (x+1)(x+2)=(3+1)(3+2)=4*5=20 3) 3^x=36-3^x-1 3^x+3^x-1=36 3^x(1+1/3)=36 3^x(4/3)=36 3^x=36(3/4) 3^x=27 3^x=3^4<-----27=3的4次方 x=4|||||1 8(x-3)=3x-x^2 x^2-3x+8x-24=0 x^2+5x-24=0 (x+8)(x-3)=0 x=3 or -8 2 (x-2)(x-3)=0 x=2 or 3 when x=2 (x+1)(x+2)=12 when x=3 (x+1)(x+2)=20 3^x=36-3^(x-1) 3^(x-1)+3^x=36 3^(x-1)(1+3)=36 3^(x-1)=9 x=3
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