Question

Solving equations help please? I don't know if I should do PEMDAS or left to right :/

Answer 1

you always do PEMDAS. If two operations are at the "same level", you do left to right.
in this problem, you have to test each choice, and see if when x = each of the numbers, you get 0 out of the equation. Only one of the choices has all 3 numbers that work.

Answer 2

for example, in choice A, x=-3 is the first value to check.
to check x= -3, replace x with (-3) (the parens help to make sure we don't make a mistake)
thus
\[ 9x^3 + 9x^2-4x-4=0 \]
becomes
\[ 9(-3)^3 + 9(-3)^2 -4(-3) -4 = 0?\]
now simplify the left side and see if you get 0.

Answer 3

that becomes
9* -27 + 9*9 +12 - 4
or
-243+81 +8
-154
and that is not zero. so x=-3 is not correct. cross off any choices that have x=-3 on their list.

Answer 4

@phi I plugged in every number and none of them equaled zero, please help?

Answer 5

because -3 does not work, choice A is not the answer.
Test the numbers given in choice B.
the first number they give is -1:
\[ 9(-1)^3 + 9(-1)^2 -4(-1) -4 = 0? \]
-1^3 means -1* -1 * -1 = -1 (work it out)
-1^2 means -1*-1 = 1
so we have
\[ 9*-1 + 9*1 + -4*-1 + -4 = 0?\]
you get
\[ -9 + 9 +4 + -4 = 0?\]
and yes, -9+9 + 4 -4 is 0, so -1 is an answer.
now check x= -2/3