#### Question

# Help with excersises?

Hi... Im doing a math project, and I need to do the following excersises... and show the work for all of them... can someone help me? thanks!

1.Solve 5x2 = –45x.

2.Solve x2 = 14x – 49.

3.Solve x2 + 18 = –9x.

4.Solve 4x2 = 12x + 40.

5.In the following equation, identify the x-intercepts in the graph y = 3x2 + 19x – 40.

6.Provide a unique real world example where quadratic equations might be used.

#### Answers

Yeah right... math project. Next time right the square sign as 2 or ^2. I'll do them it's practice for me, but you'll need to learn them eventually.

1.

5x2 = -45x

5x2 + 45x = 0

5x(x + 9) = 0

x = 0 OR x = -9

2.

x2 = 14x - 49

x2 - 14 + 49 = 0

(x - 7) (x- 7) = 0

x = 7

3.

x2 + 18 = -9x

x2 + 9x + 18 = 0

(x + 6) (x + 3) = 0

x = -6 OR x = -3

4.

4x2 = 12x + 40

x2 = 3x + 10

x2 - 3x - 10 = 0

(x - 5) (x + 2) = 0

x = 5 OR x = -2

5.

x- intercepts = fancy name for roots or when y = 0.

y = 3x2 + 19x - 40

y = (x + 8) (3x -5)

(x + 8) (3x - 5) = 0

x = -8 OR x = 5/3

6.

They describe orbits of planets as they move around the sun.

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7.

Look a lot of problems keep being recycled over and over again. Before you ask put the question on google word for word. This question has already been solved here is the answer: http://answers.yahoo.com/question/index?…

Study the solution of quadratic equations.