Question

Find the solution to the following equation by transforming it into a perfect square trinomial.

x2 – 10x = 39

A.{–3, 13}

B.{–15, 25}

C.{–20, 30}

D.{59, 69}

Answer 1

x2 – 10x = 39
split -10 into two for -5 and -5...multiply them to get 25 and add 25 to both sides
x2 – 10x +25= 39+25

Answer 2

Ok

Answer 3

x2 – 10x+25 = 64
then factor the left side and take the square root of both sides...

Answer 4

hope that was enough help

Answer 5

?

Answer 6

was it? enough help?

Answer 7

No... I don't get your second part

Answer 8

can you factor the left side?

Answer 9

Sure, what number should I factor?

Answer 10

you need to factor the polynomial... Unfoil it...

Answer 11

How do you factor a polynomial?

Answer 12

\[(x-5)(x-5)\]
do you know how to multiply those two...

Answer 13

FOIL?

Answer 14

x^2-5x-5x+25

Answer 15

Right?

Answer 16

yes...now combine like terms

Answer 17

-5x-5x = -10x

Answer 18

x^2-10x+25

Answer 19

so \[(x-5)^2=64\]

Answer 20

because \[x^2-10x+25=64=(x-5)(x-5)\]

Answer 21

Ok...

Answer 22

so take the square root of both sides of the equation \[(x-5)^2=64\]

Answer 23

How?

Answer 24

and you get \[x-5=8\] or x-5=-8

Answer 25

So...x=-3

Answer 26

\[\sqrt{(x-5)^2}=(x-5)\] and \[\sqrt{64}=\pm8\]

Answer 27

yes...x=-3 is one possible answer

Answer 28

Isn't there a more simply way of solving this type of question?

Answer 29

So the other x=13?

Answer 30

yes...completing the square is one way to do it...

Answer 31

the easier way is to simply factor the initial polynomial

Answer 32

either way...you will need to learn how to factor polynomials...

Answer 33

yup

Answer 34

multiply these two and combine like terms
\[(x+3)(x-13)\]

Answer 35

Ah, soo.. how would you factor the initial polynomial

Answer 36

Using the FOIL method?

Answer 37

Sorry, my OS is loading extremely slow

Answer 38

\[x^2-10x=39\]

Answer 39

mine is going slow too

Answer 40

subtract 39 from both sides

Answer 41

\[x^2-10x-39=0\]

Answer 42

\[x^2-x13+3x-39\]

Answer 43

factors to\[(x+3)(x-13)=0\] now either \[x+3=0\] or x-13=0

Answer 44

https://www.youtube.com/watch?v=bTe-HhNkR28

Answer 45

watch that:)

Answer 46

ooo thanks

Answer 47

yup:)