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15. Consider the quadratic with equation y = ax + bx + c that passes through the points (1, 22), (6, 7) and (5, - 2). 15a First set up a system of equations in the variables a, b and c using the points given. The first equation has been written for you: Equation 1: a+b+c 22 Equation 2: 7 36 a+ 6 b+c Equation 3: 25 -2 a+ 5 b+c 15b V Next subtract Equation 3 from both Equation 1 and Equation 2 to form two new equations that involve only a and b: Equation 1: atb+c = 22 subtract Equation 3: 25a + 5b + c -2 to give Equation 4: 24 -24 a+ (-4) b and Equation 2: 36a + 6b + c 7 subtract Equation 3: 25a + 5b + c = -2 to give Equation 5: 9 11 a + 1 b15' Consider the quadratic with equation y = at? + bx + c that passes through the points (1, 22] , (6, 7] and (5, 2] . 11. :i: J. u 6 Next rearrange Equation 5 to make .5 the subject: 0 b = 9 11:: @ Next substitute this result into Equation 4 to obtain an equation just in terms of :1, and then solve for :1. @ Substitute the value of a that you just obtained into the rearranged form of Equation 5 to obtain b: Enter your next step hen