Question

Which of the following is a solution of x2 - 8x = -27?

Answer 1

negative 4 minus i square root of 11

4 plus i square root of 11

negative 4 minus i square root of 44

4 plus i square root of 44

Answer 2

\[\large{-4 - i\sqrt{11}}\]

\[\large{4+i\sqrt{11}}\]

\[\large{-4-i\sqrt{44}}\]

\[\large{4+i\sqrt{44}}\]

Answer 3

These are the options ?

Answer 4

correct

Answer 5

Okay what do you think the answer should be and why ?

Answer 6

Have you tried it ?

Answer 7

I have but I think im trying it wrong

Answer 8

The equation given in the question is:

\[\large{x^2 - 8x = -27}\]

\[\large{\implies x^2 - 8x + 27 = 0}\]


Okay what did you try ?

Answer 9

You can compare this equation with the general quadratic equation:

\[\large{ax^2 + bx + c = 0}\]

On comparing, you can find out a,b and c. Using these values and using quadratic formula we can find out the solution of the equation:

\[\large{x = \cfrac{-b \pm \sqrt{b^2 - 4ac}}{2a}}\]

Answer 10

ohh I wrote the number different hold on let me try that

Answer 11

Sure :)

Answer 12

so I tried but im still clueless

Answer 13

Its okay. What have you tried ?

Answer 14

what I tried was wrong, how should I solve this?

Answer 15

Well follow this method:

\(\color{blue}{\text{Originally Posted by}}\) @vishweshshrimali5
You can compare this equation with the general quadratic equation:

\[\large{ax^2 + bx + c = 0}\]

On comparing, you can find out a,b and c. Using these values and using quadratic formula we can find out the solution of the equation:

\[\large{x = \cfrac{-b \pm \sqrt{b^2 - 4ac}}{2a}}\]
\(\color{blue}{\text{End of Quote}}\)

Step by step

First find out a,b and c

Answer 16

how do I find that? can u write the equation and I solve it?

Answer 17

Okay lets see:

\[\large{x^2 - 8x + 27 = 0}\]

\[\large{ax^2 + bx + c = 0}\]

Answer 18

Now lets compare both equations

Answer 19

alright

Answer 20

In first equation coefficient of x^2 = 1

In second it is = a

So, a = 1

Answer 21

Now similarly find out b

Answer 22

b is 8?
c is 27?

Answer 23

c is correct

Check the sign of b again

Answer 24

In first equation coefficient of x = -8

Answer 25

Don't forget the minus sign

Answer 26

okay so b is -8

Answer 27

@vishweshshrimali5

Answer 28

You now have the a , b , and c to use in your quadratic formula.

Answer 29

@ChristopherToni

Answer 30

can you help me? @ChristopherToni

Answer 31

Up to this point, you've determined that a=1, b=-8 and c=27. Plugging this into the quadratic formula gives us \(\large x=\dfrac{-(-8) \pm \sqrt{(-8)^2-4(1)(27)}}{2(1)}\). What do you get when you simplify this? :-)

Answer 32

I troed and I got