First, distribute 2 to the (x+3) to get:
21 = 2x+6
subtract 6 from both sides to get:
15 = 2x
Finally, we divide both sides by 2 to simplify x to:
x = 7.5 (OR) x =

(Just so you know, if you pick a brainliest answer, both you and the person who got the brainliest answer get some points.
Answer:
the y-intercept
Step-by-step explanation:
By concepts of polynomials and systems of linear equations, the constants c and d of the expression p(x) = x⁴ - 5 · x³ - 7 · x² + c · x + d are 29 and 30.
<h3>How to determine the missing coefficients of a quartic equation</h3>
A value x is a root of a polynomial if and only if p(x) = 0. We must replace the given equation with the given roots and solve the resulting system of <em>linear</em> equations:
(- 1)⁴ - 5 · (- 1)³ - 7 · (- 1)² + (- 1) · c + d = 0
- c + d = 1 (1)
3⁴ - 5 · 3³ - 7 · 3² + 3 · c + d = 0
3 · c + d = 117 (2)
The solution of this system is c = 29 and d = 30.
By concepts of polynomials and systems of linear equations, the constants c and d of the expression p(x) = x⁴ - 5 · x³ - 7 · x² + c · x + d are 29 and 30.
To learn more on polynomials: brainly.com/question/11536910
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Answer:
b
Step-by-step explanation:
the answer is b