1 variables, evaluation

Variables and Evaluation

http://www.lahc.edu/math/frankma.htm

In mathematics we use symbols such as x, y and z to represent numbers.


In mathematics we use symbols such as x, y and z to represent numbers. These symbols are called variables because their values change depending on the situation .


In mathematics we use symbols such as x, y and z to represent numbers. These symbols are called variables because their values change depending on the situation . We use variables and mathematics operations to make expressions which are calculation procedures.


In mathematics we use symbols such as x, y and z to represent numbers. These symbols are called variables because their values change depending on the situation . We use variables and mathematics operations to make expressions which are calculation procedures. For example, if an apple cost $2 and x represents the number of apples,


In mathematics we use symbols such as x, y and z to represent numbers. These symbols are called variables because their values change depending on the situation . We use variables and mathematics operations to make expressions which are calculation procedures. For example, if an apple cost $2 and x represents the number of apples, then “2x” is the expression for the cost for x apples.


In mathematics we use symbols such as x, y and z to represent numbers. These symbols are called variables because their values change depending on the situation . We use variables and mathematics operations to make expressions which are calculation procedures. For example, if an apple cost $2 and x represents the number of apples, then “2x” is the expression for the cost for x apples. Suppose we have 6 apples, set x = 6 in the expression 2x,


In mathematics we use symbols such as x, y and z to represent numbers. These symbols are called variables because their values change depending on the situation . We use variables and mathematics operations to make expressions which are calculation procedures. For example, if an apple cost $2 and x represents the number of apples, then “2x” is the expression for the cost for x apples. Suppose we have 6 apples, set x = 6 in the expression 2x, we obtain 2(6) = 12 for the total cost.


In mathematics we use symbols such as x, y and z to represent numbers. These symbols are called variables because their values change depending on the situation . We use variables and mathematics operations to make expressions which are calculation procedures. For example, if an apple cost $2 and x represents the number of apples, then “2x” is the expression for the cost for x apples. Suppose we have 6 apples, set x = 6 in the expression 2x, we obtain 2(6) = 12 for the total cost. The value “6” for x is called input (value).


In mathematics we use symbols such as x, y and z to represent numbers. These symbols are called variables because their values change depending on the situation . We use variables and mathematics operations to make expressions which are calculation procedures. For example, if an apple cost $2 and x represents the number of apples, then “2x” is the expression for the cost for x apples. Suppose we have 6 apples, set x = 6 in the expression 2x, we obtain 2(6) = 12 for the total cost. The value “6” for x is called input (value). The answer 12 is called the output.


In mathematics we use symbols such as x, y and z to represent numbers. These symbols are called variables because their values change depending on the situation . We use variables and mathematics operations to make expressions which are calculation procedures. For example, if an apple cost $2 and x represents the number of apples, then “2x” is the expression for the cost for x apples. Suppose we have 6 apples, set x = 6 in the expression 2x, we obtain 2(6) = 12 for the total cost. The value “6” for x is called input (value). The answer 12 is called the output. This process of replacing the variables with input value(s) and find the output is called evaluation.




Each variable can represent one specific measurement only.



Each variable can represent one specific measurement only. Suppose we need an expression for the total cost of apples and pears and x represents the number of apples,



Each variable can represent one specific measurement only. Suppose we need an expression for the total cost of apples and pears and x represents the number of apples, we must use a different letter, say y, to represent the number of pears since they are two distinct measurements.

Variables and EvaluationWhen evaluating an expression, replace the variables with the input-values enclosed with ( )’s.

Example A.

a. Evaluate –x if x = –6.


Example A.


When evaluating, insert the input enclosed in a “( )”.


Example A.


When evaluating, insert the input enclosed in a “( )”. Therefore, set x = (–6) we’ve–x – (–6)


Example A.


When evaluating, insert the input enclosed in a “( )”. Therefore, set x = (–6) we’ve–x – (–6) = 6


Example A.



b. Evaluate –3x if x = –6.


Example A.




–3x –3(–6)


Example A.




–3x –3(–6) = 18


Example A.




–3x –3(–6) = 18

c. Evaluate –2x2 if x = 6.


Example A.




–3x –3(–6) = 18


–2x2 –2(6)2


Example A.




–3x –3(–6) = 18


–2x2 –2(6)2 = –2(36)


Example A.




–3x –3(–6) = 18


–2x2 –2(6)2 = –2(36) = –72


Example A.




–3x –3(–6) = 18


–2x2 –2(6)2 = –2(36) = –72


d. Evaluate –4xyz if x = –3, y = –2, z = –1.

Example A.




–3x –3(–6) = 18


–2x2 –2(6)2 = –2(36) = –72



–4xyz

–4(–3)(–2)(–1)

Example A.




–3x –3(–6) = 18


–2x2 –2(6)2 = –2(36) = –72



–4xyz

–4(–3)(–2)(–1) = 24

Variables and Evaluatione. Evaluate x – y if x = –3, y = –5.

Variables and Evaluatione. Evaluate x – y if x = –3, y = –5. x – y (–3) – (–5)

Variables and Evaluatione. Evaluate x – y if x = –3, y = –5. x – y (–3) – (–5) = –3 + 5

Variables and Evaluatione. Evaluate x – y if x = –3, y = –5. x – y (–3) – (–5) = –3 + 5 = 2

f. Evaluate 3x2 – y2 if x = 2 and y = –3.



Replace x by (2) and y by (–3) in the expression, we have 3*(2)2 – (–3)2



Replace x by (2) and y by (–3) in the expression, we have 3*(2)2 – (–3)2 = 3*4 – 9 = 12 – 9



Replace x by (2) and y by (–3) in the expression, we have 3*(2)2 – (–3)2 = 3*4 – 9 = 12 – 9 = 3


g. Evaluate –x2 + (–8 – y)2 if x = 3 and y = –2.





Replace x by (3), y by (–2) in the expression, – (3)2 + (–8 – (– 2))2





Replace x by (3), y by (–2) in the expression, – (3)2 + (–8 – (– 2))2 = – 9 + (–8 + 2)2






= – 9 + (–6)2






= – 9 + (–6)2 = – 9 + 36 = 27

h. Evaluate (a – b)(b – c) if a = 3, b = –2, c = –4.Variables and Evaluation

h. Evaluate (a – b)(b – c) if a = 3, b = –2, c = –4.

(a – b)(b – c) ((3) – (–2))((–2) – (–4))



(a – b)(b – c) ((3) – (–2))((–2) – (–4)) = (3 + 2)(–2 + 4)



(a – b)(b – c) ((3) – (–2))((–2) – (–4)) = (3 + 2)(–2 + 4) = (5)(2)



(a – b)(b – c) ((3) – (–2))((–2) – (–4)) = (3 + 2)(–2 + 4) = (5)(2) = 10



(a – b)(b – c) ((3) – (–2))((–2) – (–4)) = (3 + 2)(–2 + 4) = (5)(2) = 10


i. Evaluate (2b – 3a)2 if a = –4, b = – 3.


(a – b)(b – c) ((3) – (–2))((–2) – (–4)) = (3 + 2)(–2 + 4) = (5)(2) = 10



(2(–3) –3(–4))2


(a – b)(b – c) ((3) – (–2))((–2) – (–4)) = (3 + 2)(–2 + 4) = (5)(2) = 10



(2(–3) –3(–4))2 = (–6 + 12)2


(a – b)(b – c) ((3) – (–2))((–2) – (–4)) = (3 + 2)(–2 + 4) = (5)(2) = 10



(2(–3) –3(–4))2 = (–6 + 12)2 = (6)2 = 36


(a – b)(b – c) ((3) – (–2))((–2) – (–4)) = (3 + 2)(–2 + 4) = (5)(2) = 10


j. Evaluate b2 – 4ac if a = –2, b = –3, and c = 5.


(2(–3) –3(–4))2 = (–6 + 12)2 = (6)2 = 36


(a – b)(b – c) ((3) – (–2))((–2) – (–4)) = (3 + 2)(–2 + 4) = (5)(2) = 10



(–3)2 – 4(–2)(5)


(2(–3) –3(–4))2 = (–6 + 12)2 = (6)2 = 36


(a – b)(b – c) ((3) – (–2))((–2) – (–4)) = (3 + 2)(–2 + 4) = (5)(2) = 10



(–3)2 – 4(–2)(5) = 9 + 40 = 49


(2(–3) –3(–4))2 = (–6 + 12)2 = (6)2 = 36

Exercise. Evaluate.A. –2x with the input


1. x = 3 2. x = –3 3. x = –5 4. x = –1/2

B. –y – 2x with the input5. x = 3, y = 2 6. x = –2, y = 3

7. x = –1, y = –4 8. x = ½, y = –6

C. (–x)2 with the input9. x = 3 10. x = –3 11. x = –5 12. x = –1/2

D. –x2 with the input13. x = –2 14. x = –3 15. x = –9 16. x = –1/3

E. –2x3 with the input17. x = 3 18. x = –2 19. x = –1 20. x = –½

F. 3x2 – 2x – 1 with the input21. x = – 4 22. x = –2 23. x = –1 24. x = ½

Variables and EvaluationG. –2y2 + 3x2 with the input25. x = 3, y = 2 26. x = –2, y = – 3

27. x = –1, y = –4 28. x = –1, y = –1/2

J. b2 – 4ac with the input37. a = –2, b = 3, c = –5 38. a = 4, b = –2, c = – 2 39. a = –1, b = – 2, c = –3 40. a = 5, b = –4, c = 4

H. x3 – 2x2 + 2x – 1 with the input29. x = 1 30. x = –1 31. x = 2 32. x = ½

33. a = –1, b = – 2 34. a = 2, b = –4

–b2a

I. with the input

35. a = –2, b = – 8 36. a = 2, b = – 12

Variables and Evaluation a – b c – d

K. with the input

43. a = –2, b = 3, c = –5, d = 0 44. a = –1, b = –2, c = –2, d = 14

41. a = 1, b = –2, c = 2, d = – 2 42. a = –4, b = –2, c = –1, d = –4

(a – b)(b – c) (c – d)(d – a)

L. with the input

47. a = –2, b = 3, c = –5, d = 0 48. a = –1, b = –2, c = –2, d = 14

45. a = 1, b = –2, c = 2, d = 2 46. a = –4, b = –2, c = –1, d = –4

M. b2 – a2 – c2 if 49. a = –2, b = 3, c = –5 .50. a = 4, b = –2, c = – 2

N. b2 – 4ac if 51. a = –2, b = 3, c = –5 .52. a = 4, b = –2, c = – 2

1 variables, evaluation

Education

Transcript of 1 variables, evaluation