Please help will brainlist if right

12. B

13 A

18 B

19 B

Step-by-step explanation:

12. The solutions of the quadratic is the roots, so 0 = x^2 -7x -30 = (x-10)(x+3). For this to be satisfied, either x-10 = 0 -> x = 10 and x + 3 = 0 -> x = -3

13. Either x = 0 or x+8 = 0 -> x =-8 for this to be true

18. The GCF of 2, 6, and 20 is 2. No other number satisfies being a common factor.

19. The product of the solutions of the equation is the (constant/leading coefficient) in the quadratic, which is -8/1 = -8

I hope this helps! :)

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step-by-step explanation:

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hope it you

step-by-step explanation:

sin(7pi/6 - pi/3)  

= sin(7pi/6 - 2pi/6)  

= sin(5pi/6)  

= sin(pi - pi/6)  

= sin(pi/6)  

= 1/2  

sin 7pi/6 - sin pi/3  

= sin (pi + pi/6) - sin pi/3  

= -sin pi/6 - sin pi/3  

= -1/2 - sqrt(3)/2  

= -(1+sqrt(3))2