if f (x) be a quadratic polynomial such that f (2) = -3 and f (-2) = 21 find the coefficient of 'x' in f (x)
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f(x)=a x^{2} +bx+c=0 \\ quadratic equation
f(2)=4a+2b+c=-3 -------1
f(-2)=4a-2b+c=21 ---------2
for coefficient of x
from eq. 1&2
4a+2b+c=-3
4a-2b+c=21
(-) (+) (-)=(-)
------------------
4b=-24
b=-6
f(2)=4a+2b+c=-3 -------1
f(-2)=4a-2b+c=21 ---------2
for coefficient of x
from eq. 1&2
4a+2b+c=-3
4a-2b+c=21
(-) (+) (-)=(-)
------------------
4b=-24
b=-6
extreme360:
thanks
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