Section 9.5 Solving Quadratic Equations Usingthe Quadratic Formula 521Exercises9.5Dynamic Solutionsavailable at BigIdeasMath.comIn Exercises 3–8, write the equation in standard form. Then identify the values of a, b, and c that you would use to solve the equation using the Quadratic Formula.3. x2 7x 4. x2 4x 125. 2x2 + 1 5x 6. 3x + 2 4x27.4 3x x2 + 3x 8. 8x 1 3x2 + 2In Exercises 9–22, solve the equation using the Quadratic Formula. Round your solutions to the nearest tenth, if necessary. (See Example 1.)9. x2 12x + 36 0 10. x2 + 7x + 16 011.x2 10x 11 0 12. 2x2 x 1 013.2x2 6x + 5 0 14. 9x2 6x + 1 015.6x2 13x 6 16. 3x2 + 6x 417.1 8x 16x2 18. x2 5x + 3 019. x2 + 2x 9 20. 5x2 2 4x21. 2x2 + 9x + 7 3 22. 8x2 + 8 6 9x23. MODELING WITH MATHEMATICS A dolphin jumps out of the water, as shown in the diagram. The function h 16t2 + 26t models the height h (in feet) of the dolphin after t seconds. After howmany seconds is the dolphin at a height of 5 feet? (See Example 2.)24. MODELING WITH MATHEMATICS The amount of trout y (in tons) caught in a lake from 1995 to 2014 can be modeled by the equation y 0.08x2 + 1.6x + 10, where x is the number of years since 1995. a. When were about 15 tons of trout caught in thelake? b. Do you think this model can be used to determine the amounts of trout caught in future years? Explain your reasoning.In Exercises 25–30, determine the number of real solutions of the equation. (See Example 3.)25. x2 6x + 10 0 26. x2 5x 3 027.2x2 12x 18 28. 4x2 4x 129. 1 — 4 x2 + 4x 2 30. 5x2 + 8x 9In Exercises 31–36, nd the number of x-intercepts of the graph of the function. (See Example 4.)31. y x2 + 5x 1 32. y 4x2 + 4x + 133. y 6x2 + 3x 434. y x2 + 5x + 1335. f (x) 4x2 + 3x 636. f (x) 2x2 + 8x + 8In Exercises 37–44, solve the equation using any method. Explain your choice of method. (See Example 5.)37. 10x2 + 13x 4 38. x2 3x 40 039. x2 + 6x 5 40. 5x2 2541. x2 + x 12 0 42. x2 4x + 1 043. 4x2 x 17 44. x2 + 6x + 9 16Monitoring Progress and Modeling with MathematicsMonitoring Progress and Modeling with Mathematics 1. VOCABULARY What formula can you use to solve any quadratic equation? Write the formula. 2. VOCABULARY In the Quadratic Formula, what is the discriminant? What does the value of the discriminant determine?Vocabulary and Core Concept CheckVocabularyand Core ConceptCheck