y is directly proportional to (x-1)^2. When x=5, y=4. Find y when x=7.
The trick to finding y in this question is to interpret the clue in the question of 'directly proportional'. Directly proportional means that the y and the (x-1)2 scale by the same amount. Another way of saying this is that y is equal to (x-1)2 multiplied by some constant, say C, giving us: y = C*(x-1)2From here we can calculate C by inputting the information provided: y=4 when x=5.4 = C*(5-1)2 = C42 = C16Therefore C = 0.25Finally, we substitute x=7 to find the final answer:y = 0.25*(7-1)2 = 0.2562 = 0.2536 = 9
JS
Related Maths GCSE answers
All answers ▸How do you factorise the algebraic expression x^2 +5x+ 6?
A school has a number of students. One is chosen at random; the probability that the student is female is 2/5. Knowing that there are 174 male students, work out the total number of students in the school.
Solve the simultaneous equations: 5x + 3y = 9 and 7x - 2y = 25.
Which of these fractions is the largest - 33/56 ,4/7, 9/21, 6/14