標題:
Mathematics Questions
發問:
1. One number is greater than another number . If the smaller number is subtracted from three times the greater number , the result is 78 . Find the sum of the two numbers . 2. ABCD is a square. If AB=3x+3 and BC=5x-11 , find the area of the square.3.Ifa triangle has height (10-2x)cm, base 9cm and area... 顯示更多 1. One number is greater than another number . If the smaller number is subtracted from three times the greater number , the result is 78 . Find the sum of the two numbers . 2. ABCD is a square. If AB=3x+3 and BC=5x-11 , find the area of the square. 3.Ifa triangle has height (10-2x)cm, base 9cm and area (7-x)cm square, find the value of x .
最佳解答:
1. Actually, there are many possibilities of the sum of the 2 number. Let the larger number be A, and the smaller number be B. Then, ------ A>B ------ 3A- B = 78 If we move B from the left to the right, ------3A = 78 B Assume B is very small, e.g. = 1 Then 3A must be greater than oe equal to 79. Because, 79 is not the multiple of 3, ∴ we need to find the smallest possible multiple of 3, i.e. 81 -------3A = 81 -------A = 27 Them, -------B = 3 In the situation, sum of the 2 nos. = 30 But, if -----3A = 84 -------A = 28 -------B = 6 In this situation, sum of 2 nos. = 34 ∴There are many possibilities! 2. Because ABCD = square ∴Its lengths are equal. ∴ AB = BC ∴3x 3= 5x -11 --- 14 = 2x --- x = 7 Area of the square = (3x 3)^2 --------------------- = 576 3. Area of triangle = (height x base)/2 ∴[ 9 (10-2x)] /2= 7-x --- (90-18x) /2 = 7x --- 45 - 9x = 7x --- 45 = 16x --- x = 45/16 2008-08-14 23:53:07 補充： Sorry, question 3 , typed it wrongly. ∴[ 9 (10-2x)] /2= 7-x --- (90-18x) /2 = 7-x --- 45 - 9x = 7-x --- 38 = 8x --- x = 4.75
其他解答:
Mathematics Questions
發問:
1. One number is greater than another number . If the smaller number is subtracted from three times the greater number , the result is 78 . Find the sum of the two numbers . 2. ABCD is a square. If AB=3x+3 and BC=5x-11 , find the area of the square.3.Ifa triangle has height (10-2x)cm, base 9cm and area... 顯示更多 1. One number is greater than another number . If the smaller number is subtracted from three times the greater number , the result is 78 . Find the sum of the two numbers . 2. ABCD is a square. If AB=3x+3 and BC=5x-11 , find the area of the square. 3.Ifa triangle has height (10-2x)cm, base 9cm and area (7-x)cm square, find the value of x .
最佳解答:
1. Actually, there are many possibilities of the sum of the 2 number. Let the larger number be A, and the smaller number be B. Then, ------ A>B ------ 3A- B = 78 If we move B from the left to the right, ------3A = 78 B Assume B is very small, e.g. = 1 Then 3A must be greater than oe equal to 79. Because, 79 is not the multiple of 3, ∴ we need to find the smallest possible multiple of 3, i.e. 81 -------3A = 81 -------A = 27 Them, -------B = 3 In the situation, sum of the 2 nos. = 30 But, if -----3A = 84 -------A = 28 -------B = 6 In this situation, sum of 2 nos. = 34 ∴There are many possibilities! 2. Because ABCD = square ∴Its lengths are equal. ∴ AB = BC ∴3x 3= 5x -11 --- 14 = 2x --- x = 7 Area of the square = (3x 3)^2 --------------------- = 576 3. Area of triangle = (height x base)/2 ∴[ 9 (10-2x)] /2= 7-x --- (90-18x) /2 = 7x --- 45 - 9x = 7x --- 45 = 16x --- x = 45/16 2008-08-14 23:53:07 補充： Sorry, question 3 , typed it wrongly. ∴[ 9 (10-2x)] /2= 7-x --- (90-18x) /2 = 7-x --- 45 - 9x = 7-x --- 38 = 8x --- x = 4.75
其他解答:
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