Vikas TU
Last Activity: 11 Years ago
The inequality y(-1)> -4 , y(1)< 0 , & y(3)> 5 are known to hold for y = ax2 + bx + c then the satisfy all the value and marks the eqns. given below:
Given that
y = ax^2 + bx + c
y(-1) > -4
therefore,
a*(-1)^2 + b(-1) + c > -4
a - b + c > -4 ..........................(i)
and
y(1) < 0
a + b + c < 0
or
-a -b -c > 0 ............................(ii)
and
y(3) > 5
9a + 3b +c > 5 .............................(iii)
Adding eq. (i) and eq. (iii)
10 a + 2b + 2c >1
i.e. 5 a + b + c > 0.5 .......................(iv)
Adding eq.s (ii) and (iv) we get,
4a > 0.5
8a > 1
thus, a > 1/8
(D) is the answer.
PLZ APPROVE!