careless850 3 years ago Can someone please explain and show me how to do these please. 1.) x^2 – 8x + 15 2.) a^2 – a – 20 3.)a^2 – 5a – 20 4.)a^2 + 12ab + 27b^2 5.)2a^2 + 30a + 100

1. careless850

@Roya Could you help me?

2. careless850

Anyone?

3. dpaInc

all of 'em?

4. Roya

dear i 'll . u need to find out x and a ?

5. careless850

Yes please. Well, yeah. :/ It's factoring trinomials.

6. careless850

7. Roya

x^2-8x+15=0 (x-3)(x-5)

8. Roya

for ex for this one think about two numbers which their multiple product be 15 and their product of sum be -8

9. Roya

we know that 3*5 is 15 and we check if the some of them is -8 or not ? 5+3=8 but with a little experience we guess -3+-5=-8

10. careless850

I see.

11. Roya

20=10*2 10*2=8 10-2=8 20=5*4 5+4=9 5-4=1 4-5=-1 so can u find out the factors ?

12. careless850

10 and 5

13. Roya

u mean (a-10)(a-5) ?

14. careless850

Wait, which one are we on?

15. careless850

The second one?

16. Roya

second

17. careless850

I'd say the factors would be -10 and -5.

18. Roya

look at what i wrote before . 4-5=-1 4*-5=-20

19. careless850

(a-1) (a-10)

20. careless850

not -10 I meant a-1 * a-20

21. Roya

a^2-11a+10 is it ur equation ?

22. Roya

a^2-21a+20 is it ur equation

23. careless850

So confusing. :/

24. Roya

don't be confuse it's need just practice . look at what i done

25. Roya

for second one as i wrote before the answer is : a-5*a+4

26. careless850

ok..

27. Roya

i think the third one is not correct but let's check forth one :

28. careless850

The question for #2 is, a^2 – a – 20. So, I have to find the product of -a and the sum of -20, right?

29. careless850

All those up top are questions, I have to factor all of them.

30. Roya

u know (a+b)^2= a^2+2ab+b^2 can u guess what we should put in my equation instead b ? because u see that first term didn't change

31. Roya

ok i solve num 3 as well but first the easier

32. careless850

Let's do #2, again.

33. careless850

a^2 – a – 20

34. Roya

ok

35. careless850

What would I do first?

36. Roya

for factories as i remember we have some ways can u tell me the ways ?

37. careless850

Find the product of one and the sum of another.

38. Roya

plz tell me all the method

39. careless850

I don't know..

40. Roya

one is (x+b)(x+a)=x^2+(a+b)+ab that's what u mentioned .

41. Roya

fortunately we can solve #2 with this : so look at 20 tell me product of which numbers make 20?

42. careless850

10*2

43. careless850

and 1- - 2 = 8

44. careless850

10 - 2 = 8

45. careless850

so 10 and 8?

46. Roya

look at our formula coefficient of x is equal to sum of the numbers , am i correct ?

47. careless850

Yse.

48. Roya

ok now tell me is the sum of 10 and 2 equal to -1 ?

49. careless850

10 + 2 = 12. 12 + (-13) = -1

50. Roya

dear now what's ur number ? check them

51. careless850

The sum of 10 and 2 is 12, right?

52. Roya

yes

53. careless850

Okay, so the sum of 10 and 2 isn't -1.

54. careless850

....

55. Roya

dear don't be confuse . may i know what's ur grade ? high school ?

56. careless850

9th.

57. Roya

where r u from ?

58. careless850

I just need to complete these 5 questions for my assignment or I get kicked out of my class. I'm from USA.

59. Roya

dear i'm here till tomorrow morning and i'll help u . u r just 16 years old . never mind dear no one kick u out

60. Roya

lets learn it again with each other ok ? ready ? fasten ur seat belt

61. careless850

I'm 17. I've failed Algebra 3 times. I just don't understand it. I'd be graduated by now if it wasn't for Algebra.

62. Roya

u r a genius . may i know ur name ?

63. careless850

Possibly. What's yours?

64. Roya

dear algebra is sweet if u touch it and guess it .

65. Roya

my name is roya . i'm iranian and i'm 21 . i'm electrical engineering student and mu=y name means dream . any thing else ? i'm a girl

66. careless850

Ha. I'm a boy, 17 the name is Dylan and I'm from Florida.

67. Roya

68. careless850

My name is Careless because eeveryone calls me that and I don't care about anything but computers and programming and processing. Yes, I'm ready. Let's start with #2... again. please.

69. Roya

dear look at # 2 . and compare it with our formula a^2-a-20

70. Roya

our formula for this one is x^2+(a+b)x+ab

71. careless850

ok..

72. Roya

so we should find 2 numbers which their mlt = -20 and their sum = -1 ok ?

73. Roya

mlt=multiple

74. careless850

ok.

75. Roya

so tell me the numbers which their mlt = -20

76. careless850

-10 * 2

77. Roya

can u tell me their sum ?

78. careless850

sum of...?

79. careless850

-10 + 2?

80. Roya

as u and me know their sum is 10-2 =8 ok ?

81. Roya

or as u wrote -10+2=-8

82. careless850

ok..

83. Roya

none of them are equal to -1 . am i right ?

84. careless850

Right.

85. Roya

so let's try another numbers . tell me two other number's which mlt=-20

86. careless850

-5*4

87. Roya

ok and tell me the sum

88. careless850

-5 + 4 = -1///

89. careless850

(x-5) (x+4) .... ^_^

90. Roya

so u find two numbers which mlt=-20 and sum = -1 so put them in our formula

91. Roya

such a genius boy . u should proud of urself .

92. Roya

know multiple two terms to check ur answer .

93. careless850

So, I got it right?

94. Roya

ok i give u another ex and plz solve it for me .

95. Roya

x^2+5x+6

96. careless850

ok...

97. careless850

mlt of 5 and sum of 6.. is....

98. Roya

oh oh ! mlt=6 sum=5

99. careless850

2.5 * 2 = 5 and 3* 2 = 6...

100. careless850

ohhhhhhhhhhhhhhhhhhhhhhhhhhhhhh...

101. Roya

note that u can't change the number for sum and mlt

102. careless850

3*2 = 6 and 3+2 = 5...

103. Roya

fantastic so put them in formula

104. careless850

(x+3) (x+2)

105. Roya

great job , look at this one : x^2+11x+18

106. Roya

first tell me the mlt and sum :

107. careless850

9-2 = 18 and 9+2 = 11. (x+9) (x+2)

108. careless850

9*2*

109. careless850

9*2 = 18 and 9+2 = 11.

110. Roya

9-2 no 9*2 dear yes u solve it .

111. careless850

I get THOSE.. why can't I get M questions...

112. careless850

Like this.. a^2 – 5a – 20..

113. careless850

sum of 5 and mlt of 20..

114. careless850

sum of -5 and -20*

115. Roya

it's a bit more difficult

116. careless850

Ugh. Sum of -5 and mlt of -20.**

117. careless850

How so? What do I have to do now?

118. careless850

HEY. I'm going to close this question and open another one. This one is getting laggy.