Question

What would be the most logical first step to solve this quadratic equation?

x2+2x+13=8

Answer 1

what level is this? (that equation only has imaginary roots and, without stereotyping, most people who know about imaginary numbers can solve quadratics)

Answer 2

just use ur quadtratic equatin and substitute.

Answer 3

so would it be the square root of both sides .

Answer 4

is it x^2?

Answer 5

Did you make up this question yourself?

Answer 6

no its algebra twilight math class .

Answer 7

its not complicated, just put in the quadtratic formula, the values of Ax +Bx +C=0, where in ur case, its x^2 +2x +5 =0..... or am i missing something...

Answer 8

Hmm. Well the first step would be to either set it to 0, or complete the square. It won't factorise, so I'd complete the square. But you'll still need to square root a negative number.

Answer 9

i dont know how to do that sorry im not qood at math worse subject evr .

Answer 10

Note
\[\sqrt{-1} = i \]

Answer 11

where do u see a negative value?

Answer 12

nvm is see it now...

Answer 13

{ -2 ± Sq Root ( 4 - 20 ) } / 2

Answer 14

unless u use imaginary numbers, thats as simplified as it gets...

Answer 15

subtract the right hand side from both sides of the equation would be the first step

Answer 16

x2+2x+13 -8=8 -8

x^2 +2x +5 = 0

Answer 17

the next step would be to "complete the square".... if you dont know the quadratic formula that is :)

x^2 +2x +5 = 0 ; subtract 5 from both sides


x^2 +2x + ___ = -5 + ____

we need to find a suitable number to fill in these blanks with; we need to create a "perfect" square trinomial that will factor into: (x+?)^2

we know that the product of a binomial and itself is:

(a+b)(a+b) = a^2 +2ab + b^2

what we have is: a^2 +a(2__ ) + (___)^2

Answer 18

I know the quadratic formula, but would still complete the square.

Answer 19

if I recall correctly, completing the sqaure is how we get the quadratic formula :)

Answer 20

Affirmative.

Answer 21

lol.

Answer 22

man im in university calc, and i dont even remember how to complete the square...havent done that since 9th grade haha

Answer 23

(a+b)(a+b) = a^2 +2ab + b^2

what we have is: a^2 +a(2__ ) + (___)^2

we see that if we divide the midde term by 2a we will get a suitable "b" right?

x^2 +2x +5 ....2x/2x = 1...b=1 b^2 = 1

Answer 24

pellet, university calc. That's harcore.

Answer 25

hardcore* :@

Answer 26

x^2 +2x +1 = -5+1

(x+1)^2 = -4 already see a problem lol

x+1 = +-sqrt(-4)

x = -1 +- sqrt(-4)

Answer 27

its also really hard, and i dont know why i need it if im in software engineering, but ok...

Answer 28

Because Maths is everything.

Answer 29

x = -1 +- 2i :) but thats a complex number and not a "real" number

Answer 30

\[x^2 + 2x + 13 = 8 \]
\[\iff (x+1)^2 = -4 \]
\[\implies (x+1) = \pm \sqrt{-4} = \pm \sqrt{-1}\sqrt{4} = \pm 2i \]
\[\implies x = -1 \pm 2i \]

Answer 31

sorry had that typed out but realised you were explaining it so waited - but didn;t want all that typing to go to waste.

Answer 32

lol ..... you did good ;)

Answer 33

does that make any sense miranda?

Answer 34

... :(

Answer 35

im sure thats a yes ;)