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中三數學題

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1.周老闆今年以50000元購入機器一台,若它的折舊率每年是15%的話,問若干年後,它的售價只值36125元?2.真方位角:089º , 120º ,210º ,288º , 332º (求羅盤方位角)3.羅盤方位角:N25ºE , S77ºE, S17ºW, S37ºW , N45ºW (求真方位角)4.指數定律 (求x) 1. 343^x= 1/^3√49 2. 4^-x+1 - 1/256 = 0 3. 2^3x-1=4^x=24.... 顯示更多 1.周老闆今年以50000元購入機器一台,若它的折舊率每年是15%的話,問若干年後,它的售價只值36125元? 2.真方位角:089o , 120o ,210o ,288o , 332o (求羅盤方位角) 3.羅盤方位角:N25oE , S77oE, S17oW, S37oW , N45oW (求真方位角) 4.指數定律 (求x) 1. 343^x= 1/^3√49 2. 4^-x+1 - 1/256 = 0 3. 2^3x-1=4^x=2 4. (1/2)^x=16 5. 10^x+2=0.1 6. 5^2x=√125 7. 4^3-2x=16 8. (2^2)^2x-3=64 5.求下列二次方程的根。 1.x(x-3)=0 2.(x+5)^2=0 3.x^2=12x 4.(x+1)(3x-2)=0

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1. 設 n 年後售價為36125 元。 50000 * (1 - 15%)^n = 36125 0.85^n = 0.85^2 n = 2 2 年後售價為 36125 元。 ===== 2. 真方位角 = 089° 羅盤方位角 = N89° E 真方位角 = 120° 羅盤方位角 = S (180-120)° E = S 60° E 真方位角 = 210° 羅盤方位角 = S (210-180)° W = S 30° W 真方位角 = 288° 羅盤方位角 = N (360-288)° W = N 72° W 真方位角 = 332° 羅盤方位角 = N (360-332)° W = N 28° W ===== 3. 羅盤方位角 = N 25° E 真方位角 = 025° 羅盤方位角 = S 77° E 真方位角 = 180° - 77° = 103° 羅盤方位角 = S 17° W 真方位角 = 180° +17° = 197° 羅盤方位角 = S 37° W 真方位角 = 180° + 37° = 217° 羅盤方位角 = N 45° W 真方位角 = 360° - 45° = 315° 4. 1. 343^x = 1/ 3√49 (7^3)^x = 1/(7)^(2/3) 7^(3x) = 7^(-2/3) 3x = -2/3 x = -2/9 2. 4^(-x+1) - (1/256) = 0 4^(-x+1) = 1/256 4^(-x+1) = 4^(-4) -x+1 = -4 x-1 = 4 x = 5 3. 2^(3x-1) = 4^(x+2) 2^(3x-1) = (2^2)^(x+2) 2^(3x-1) = (2)^(2x+4) 3x-1 = 2x+4 x = 5 4. (1/2)^x = 16 (2^-1)^x = 2^4 2^-x = 2^4 -x = 4 x = -4 5. 10^(x+2) = 0.1 10^(x+2) = 10^(-1) x+2 = -1 x = -3 6. 5^2x = √125 5^2x = (5^3)^(1/2) 5^2x = 5^(3/2) 2x = 3/2 x = 3/4 7. 4^(3-2x) = 16 4^(3-2x) = 4^2 3-2x = 2 -2x = -1 x = 1/2 8. (2^2)^(2x-3) = 64 2^(4x-6) = 2^6 4x-6 = 6 4x = 12 x = 3 ===== 5. 1. x(x - 3) = 0 x = 0 或 x - 3 = 0 x = 0 或 x = 3 2. (x + 5)^2 = 0 x = -5 (重根) 3. x^2 = 12x x^2 - 12x = 0 x(x - 12) = 0 x = 0 或 x - 12 = 0 x = 0 或 x = 12 4. (x + 1)(3x - 2) = 0 x + 1 = 0 或 3x - 2 = 0 x = -1 或 x = 2/3

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