If y is directly proportional to x^2 and y=1/8 when x=1/2, what is the positive value of x when y=9/2? a) 3/4 b) 3/2 c) 9/4 d) 3 e) 9 what i did: y: 1/8 x^2: 1/4 1/8 * 36 = 9/2 therefore 1/4 * 36 = 9 but the answer is 3, not 9...
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Hello juliak Originally Posted by juliak If y is directly proportional to x^2 and y=1/8 when x=1/2, what is the positive value of x when y=9/2? a) 3/4 b) 3/2 c) 9/4 d) 3 e) 9 what i did: y: 1/8 x^2: 1/4 1/8 * 36 = 9/2 therefore 1/4 * 36 = 9 but the answer is 3, not 9... Translate the phrase " is directly proportional to " in symbols as: , where is a constant Then plug in the two values that you've been given: When . So: So the equation is: When : Grandad
Originally Posted by juliak If y is directly proportional to x^2 and y=1/8 when x=1/2, what is the positive value of x when y=9/2? a) 3/4 b) 3/2 c) 9/4 d) 3 e) 9 what i did: y: 1/8 x^2: 1/4 1/8 * 36 = 9/2 therefore 1/4 * 36 = 9 but the answer is 3, not 9... If y is directly proportional to x² both values have to satisfy the equation: for a certain proportionality factor k. You know Solve for k. Then plug in into the equation and solve for x.
Originally Posted by juliak If y is directly proportional to x^2 and y=1/8 when x=1/2, what is the positive value of x when y=9/2? a) 3/4 b) 3/2 c) 9/4 d) 3 e) 9 what i did: y: 1/8 x^2: 1/4 1/8 * 36 = 9/2 therefore 1/4 * 36 = 9 but the answer is 3, not 9... Because, just as "1/4" was x^2= (1/2)^2 so is this 9= x^2. You need to take the square root to get x.
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