X=the number we have to find.
This expression "2(x+9)" is when the sum of a number and nine is doubled.
If the result is seven less than the number, we will have: x-7
We can suggest the following equation:
2(x+9)=(x-7)
2x+18=x-7
2x-x=-7-18
x=-25
answer: the number would be: -25.
Answer:
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Step-by-step explanation:
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Answer:
y = x³ + 10.5x² + 31x + 13
Step-by-step explanation:
Complex roots (roots that have imaginary terms) always come in conjugate pairs. So if one root is -5 + i, there's another root that's -5 − i.
So the polynomial is:
y = (x + 1/2) (x − (-5 + i)) (x − (-5 − i))
Distributing:
y = (x + 1/2) (x² − (-5 + i)x − (-5 − i)x + (-5 + i)(-5 − i))
y = (x + 1/2) (x² + 5x − ix + 5x + ix + (-5 + i)(-5 − i))
y = (x + 1/2) (x² + 10x + (-5 + i)(-5 − i))
y = (x + 1/2) (x² + 10x + 25 + 5i − 5i − i²)
y = (x + 1/2) (x² + 10x + 25 + 1)
y = (x + 1/2) (x² + 10x + 26)
y = x(x² + 10x + 26) + 1/2(x² + 10x + 26)
y = x³ + 10x² + 26x + 1/2x² + 5x + 13
y = x³ + 10.5x² + 31x + 13