Answer:
Sum of the first 15 terms = -405
Step-by-step explanation:
a + 3d = -15 (1)
a + 8d = -30 (2)
Where,
a = first term
d = common difference
n = number of terms
Subtract (1) from (1)
8d - 3d = -30 - (-15)
5d = -30 + 15
5d = -15
d = -15/5
= -3
d = -3
Substitute d = -3 into (1)
a + 3d = -15
a + 3(-3) = -15
a - 9 = -15
a = -15 + 9
a = -6
Sum of the first 15 terms
S = n/2[2a + (n − 1) × d]
= 15/2 {2×-6 + (15-1)-3}
= 7.5{-12 + (14)-3}
= 7.5{ -12 - 42}
= 7.5{-54}
= -405
Sum of the first 15 terms = -405
It would be in the fourth quadrant because x is positive and y is negative. The quadrants are labeled in counter-clockwise order, starting in the upper-right.
Answer: 2x + 5y = - 10, Cy + 4 = (x-5)
Dy - 4 = (x+ 5)
Step-by-step explanation:
Equation of the line
5x - 2y = -6
Conditions for perpendicularity
m1 x m2 = -1
To get m1, rearrange the equation
2y = 5x + 6
y = 5x/2 + 3
n1 = 5/2 and m2 = -2/5
To get C
y = mx +c
-4 = -2 x 5/5 + C
-4 = -2 + C
C = -4 + 2
C = -2
To get the equation of the second line
y = -2x/5 - 2
Multiply through by 5
5y = -2x - 10
2x + 5y = 10.
