Question

the 6th term of an ap is -10 and the 10th term is -26 determine the 15 th term of AP

Answer 1

HeyHere is your answer,A6 = -10An = a + (n-1) da + 5d = -10_______eq.1A10 = -26a + 9d = -26_______eq.2solving both the equations by elimination method,a + 5d = -10a + 9d = -26_________-4d = 16D = -16/4D = -4Substitute the value of d = -4 in equation 1,a + 5 x (-4) = -10a = -10+20a = 10A.P. : 10, 10-4, 10+2(-4) , 10+3(-4)= 10,6,2,-2 A15 = 10+14x(-4)= 10-56 = -46Hope it helps you!

Answer 2

let the first term of an A.P. be a and common difference =d . 6th term =a+5d= -10 and 10th term = a+9d= -26 . a+9d-(a+5d)= -26+10 = -16=>4d= -16=>
d= -4 . a+5d= -10=> a+5(-4)= -10=> a=10. The 15 th term of an A.P. =a+14d =10+14(-4)= -46 . Hope it helps you...