Question

Help me please? Did I get it right?
solve x^2-2x+85=0

A. {3+7i, 3-7i}
B. {2+9i, 2-9i}
C. {2+19i, 2-19i}
D. {7+3i, 7-3i}

Is the answer B?

Answer 1

where is the part you have done so far

Answer 2

Do you know how to synthetically divide and prove why you got B

Answer 3

^^^^^^ That kind of dividing have you seen that before?

Answer 4

I've seen it, but I don't exactly remember how to use it

Answer 5

@doulikepiecauseidont

Answer 6

OK well we'll walk through it with a very easy example

Answer 7

Say you want to divide \[\Large \frac{x^3+3x^2+3x+1}{x+1}\]

That can be painstaking to go and long divide, so we have a shortcut, called synthetic division that we use

So what we do is take the denominator (what we're dividing by) and going to set it equal to 0 (you'll see why in a second)

x+1=0
x= -1

This -1 is what we'll use to go and synthetically divide

Answer 8

Ok and now we're going to take the x^3+3x^2+3x+1 and we're going to take the coefficients and line them up (if there is a missing term like if there wasn't a x^2 term, we would put a 0 in it's place, it's important you remember that

Answer 9

Step 1 is we bring the first coefficient down

Answer 10

Step 2, we multiply our -1 by 1 and write it below the 2nd term

Answer 11

Step 3 we subtract those two numbers