Pairs of integers that multiply to give +8:
1, 8
-1, -8
2, 4
-2, -4
Hmm....none of these add to give -2, so looks like this expression is unfactorable.
Plan B: Use the quadratic formula.
find the zeros:
x^2 - 2x + 8
3 answers
-b +-sq root of b^2-4ac all of this divided by 2a
2 +- sq root (-2)^2 -4(1)(8)
all divided by 2(1)
2 +- sq root 4-32
2+- sq root -28 all divided by 2
2+- 2i sq root of 7 comes from
4(-1)(7)
all divided by 2 reduces to
1 +i sq rt 7, 1-i sq rt 7 are the roots. or are the values of x.
2 +- sq root (-2)^2 -4(1)(8)
all divided by 2(1)
2 +- sq root 4-32
2+- sq root -28 all divided by 2
2+- 2i sq root of 7 comes from
4(-1)(7)
all divided by 2 reduces to
1 +i sq rt 7, 1-i sq rt 7 are the roots. or are the values of x.
Excellent!
1 answer