Question 4 - 16 marks You should use algebra in all parts of this question, showing your working clearly. (a) Solve the following equations, giving your answers as integers or as fractions in their simplest form. (i) 7x + 19 =21 - 3x [2] (ii) 14 - 3 (92 - 2) = 6 + 3x [3] 20 (iii) x + 2 2 + 8 [3] (b) Factorise the expression x2 + 13x - 68, and hence solve the equation + 13x - 68 = 0. [3] (c) A student was asked to rearrange the formula 10a = = d - 2c(6 - d) to make d the subject (assuming that 1 + 14c / 0). The student's incorrect attempt is shown below. 10 a = 4 -2c(6-d) Clear the fractions By multiplying By 7 10 a = d - 2c(6 -d Multiply out the Bracket 10 a = d -12c-2cd Collect the d terms 10 a + 12c= d-2cd Factorise 10 a + 12c= d(1 - 2c) Divide By 1 - 2c to Give d = 10 a + 12c 1-20 (i) Write out a correct rearrangement of the formula. [3] (ii) Identify and explain, as if directly to the student, two of the mistakes they have made. [2] page 7 of 9