18. Find the equation for a line which passes through the points (-8, 9) and (-6, 3). Write the equation in slope-intercept form. Show work. 19. Find the exact solutions and simplify as much as possible: 5x = 6x + 3. Show work. 20. Let f (x) = 3x + 9 and g(x) = x - 2. (a) Find the composite function (f o g)(x) and simplify. Show work. (b) Find (fog)(-3). Show work. 21. A projectile is launched from a platform 6 feet high with an initial velocity of 80 feet per second, The height h of the projectile at / seconds after launch is given by h = -16t- + 80t + 6 feet. (a) How many seconds after launch does the projectile attain maximum height? Show work. (b) What is the maximum height? Show work. x+5 22. Solve: 28 Show work. x+7 x2 -49 23. Suppose that cos 0 = 12/13 and that O is a Quadrant IV angle. (a) Find the exact value of sin 0. Show work. (b) Find the exact value of sin(20). Show work. 24. Prove the identity 1 - (cos x - sin x) = sin 2x