What is the sum of 11 terms of an arithmetic progression if the 4th term is 11 and the 7th term is -4?
-75
55
11
100
C.
11
tn= a + (n -1)d
11 = a + (4 - 1)d
11 = a + 3d ...(i)
tn = a + (n - 1)d
-4 = a + (7 - 1)d
-4 = a + 6d ...(ii)
Solving (i) and (ii), we get
a = 26, d = -5
Now,
What is the reflection of the point (-1, 3), in the line x = -4?
(-7, -3)
(-7, 3)
(7, -3)
(7, 3)
The co-ordinates of the centroid of a Δ ABC are (1, -4). What are the co-ordinates of vertex C if co-ordinates of A and B are (3, -4) and (0, 5) respectively.
(0, 13)
(0, 5)
(0, -5)
(0, -13)
D and E are points on side AB and AC of Δ ABC. DE is parallel to BC. If AD : BD = 2 : 5 and area of Δ ABC is 98 cm2, what is the area (in cm2) of quadrilateral BDEC?
90 cm2
98 cm2
94 cm2
86 cm2