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question:One root of the equation 7x^2 + mx 6 = 0 is 3. What is the other root?
answer:First, rewrite the equation for clarity: 7x^2 + mx - 6 = 0. According to Vieta's formulas, the product of the roots (alpha beta) of a quadratic equation ax^2 + bx + c = 0 is given by frac{c}{a}. For our equation, it would be frac{-6}{7}. Given that one of the roots (alpha) is -3, we can find the other root (beta) by: [ alpha beta = frac{-6}{7} ] [ -3 cdot beta = frac{-6}{7} ] [ beta = frac{-6}{7} div -3 = frac{-6}{7} cdot frac{-1}{3} = frac{6}{21} = frac{2}{7} ] Thus, the other root is boxed{frac{2}{7}}.
question:Given positive integers x and y such that x neq y and frac{1}{x} + frac{1}{y} = frac{1}{15}, determine the smallest possible value for x + y.
answer:Starting with the given condition: [ frac{1}{x} + frac{1}{y} = frac{1}{15} ] Multiplying through by xy and rearranging, we obtain: [ xy - 15x - 15y = 0 ] To apply Simon's Favorite Factoring Trick, add 225 to both sides: [ xy - 15x - 15y + 225 = 225 ] Factorizing gives: [ (x-15)(y-15) = 225 ] We seek the minimal x+y. This occurs when x-15 and y-15 are factor pairs of 225 that are close to each other in value. The factor pairs of 225 are (1, 225), (3, 75), (5, 45), (9, 25), (15, 15). Since x neq y, we ignore (15, 15). The pair (9, 25) gives the smallest sum: [ x = 9 + 15 = 24, quad y = 25 + 15 = 40 ] Thus, x+y = 24 + 40 = boxed{64}.
question:The reverse of a twodigit number, with both digits different from zero, is the number obtained by switching the order of its digits. For example, the reverse of 25 is 52 and the reverse of 79 is 97. Which of the numbers below is not the sum of a twodigit number and its reverse? A) 44 B) 99 C) 121 D) 165 E) 181
answer:1. **Define variables and setup:** Let's consider a two-digit number ( n ) where ( a ) is the tens digit and ( b ) is the units digit. Thus, we can represent ( n ) as: [ n = 10a + b ] Since both ( a ) and ( b ) are digits between 1 and 9 (inclusive), the reverse of ( n ) can be written as: [ text{reverse of } n = 10b + a ] 2. **Sum of the number and its reverse:** When we add ( n ) and its reverse, we get: [ (10a + b) + (10b + a) ] This can be simplified by combining like terms: [ = 10a + b + 10b + a = 11a + 11b = 11(a + b) ] Hence, the sum of a number and its reverse is always a multiple of 11. 3. **List and analyze given options:** We now examine the provided options to check which one is not a multiple of 11: - ( 44 ) - ( 99 ) - ( 121 ) - ( 165 ) - ( 181 ) We will test the divisibility by ( 11 ) for each: 4. **Check each option for divisibility by 11:** - ( 44 div 11 = 4 quad text{(integer, hence multiple of 11)} ) - ( 99 div 11 = 9 quad text{(integer, hence multiple of 11)} ) - ( 121 div 11 = 11 quad text{(integer, hence multiple of 11)} ) - ( 165 div 11 = 15 quad text{(integer, hence multiple of 11)} ) - ( 181 div 11 = 16.454545ldots quad text{(not an integer, hence not a multiple of 11)} ) 5. **Conclusion:** Since the sum of a number and its reverse must be a multiple of 11, and 181 is not a multiple of 11, we conclude: [ boxed{E} ]
question:Ms. Snow's math class, the ratio of girls to boys is 4:3. Including Ms. Snow, the total count of people in the room stands at 43. How many girls are in Ms. Snow's math class?
answer:- Let the number of girls be 4k, and the number of boys be 3k. - Including the teacher, the total count becomes 4k + 3k + 1 = 43. - Simplify and solve the equation: 7k + 1 = 43, then 7k = 42, thus k = 6. - The number of girls is 4k = 4 times 6 = boxed{24}.