We notice a factor of 2x in both
2x(5x^2+4x-3)
trial and error
(5x-3)(x+1) yeilds 5x^2+2x-3, nope
(5x+3)(x-1) yeilds 5x^2-2x-3, nope
(5x-1)(x+3) yeilds 5x^2+14x-3, nope
(5x+1)(x-3) yeilds 5x^2-14x-3, nope
simplest form is
2x(5x^2+4x-3)
1/3 of 39,900 equals 1/3*39900
(1/3)*(39900/1)= 39900/3
39900/3= 13300
Final answer: 13,300
If you want to solve this problem using formulas, there are two important formulas:
t1 = first term = -5
tn = nth term = last term = -5
n = numbr of terms
Sn = sum of the n terms
tn = t1 + (n - 1)d ---> 65 = -5 + (n - 1)(5)
65 = -5 + 5n - 5
65 = -10 + 5n
75 = 5n
n = 15
Sn = n(t1 + tn)/2 ---> Sn = 15(-5 + 65)/2
Sn = 450
So ur answer rounds up to 450
Letter c
:)
hope i helped
~Luis
