MATH 115 Precalculus Summer, 2017, V3.1 SHORT ANSWER, with work required to be shown, as indicated. 18. Find the equation for a line which passes through the points (5, 2) and (7, -8). Write the equation in slope-intercept form. Show work. 19. Find the exact solutions and simplify as much as possible: 2x- =7 + 4x. Show work. 20. Let f (x) = 3x- - 4 and g(x) = x-3. (a) Find the composite function (fog)(x) and simplify. Show work. (b) Find (fog)(-2). Show work. 21. A projectile is launched from a platform 12 feet high with an initial velocity of 72 feet per second, The height h of the projectile at / seconds after launch is given by h = -161 + 721 + 12 feet. (a) How many seconds after launch does the projectile attain maximum height? Show work. (b) What is the maximum height? Show work. 22. Solve: . x+7 24 =0. Show work. x+3 x- -9 23. Suppose that sin e = 4/5 and that e is a Quadrant II angle. (a) Find the exact value of cos e. Show work. (b) Find the exact value of sin(20). Show work. 24. Prove the identity (cos x - sin x) + sin(2x) = 1 Page 6 of 7