Most Important Selected Qs for JEE AdvancedMathematicsSequences and Series
Let (x^2+3 x+2 ), (x^2-x-10 ) and (x^2+x-4+y^2 ) are first three positive terms of an A.P., such that their squares will form a G.P., then which of the following is true?
Options
- ASum of all possible integral value(s) of x is -3 .
- BIf y, y+3 and z are in A.P., then z is equal to 6.
- CHarmonic mean of given numbers is 2 .
- DSum of first 20 terms of this A.P. is 40 .
Correct answer
D. Sum of first 20 terms of this A.P. is 40 .
Step-by-step solution
x^2+3 x+2, x^2-x-10 and x^2+x-4+y^2 are in A.P. as well in G.P. array ll & x^2+3 x+2=x^2-x-10=x^2+x-4+y^2 & x=-3, y=0 array Each number is equal to 2 .