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Which value for x makes the open sentence true?

9 • 8 – 2x + x2 ≥ x3 + x2



A: 7

B: 6

C: 5

D: 4

1 Answer

1 vote
basically either subsitute or solve
I will simplify to make easier work
so PEMDAS
Parenthasees
Exponents
multiply or divide whichever comes first
add or subtract whichever comes first

9 times 8=72
I will assume that x2=x^2 or x squared so left is simplified
x^3+x^2 so

72-2x+x^2>x^3+x^2
subtract x^2 from both sides since they cancel each other out
72-2x > x^3
add 2x to both sides
72 > x^3+2x
factor
72 > x(x^2+2)

now subsitute 7,6,5,4
if x=4 then
4(4^2+2)=4(16+2)=4(18)=72
72 > 72
true
since all the other numbers are smaller, the only sentence that will work is 7 or A

the answer is A 7
User ProcolHarum
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