f(x)=a In |x|+bx2+x has its extremum values at x = – 1 and x = 2 then a + 2b =
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ax+2bx+1=0atx=−1,2−a−2b+1=0∣a2+4b+1=0a+2b=1 ∣a+8b=−2⇒b−−12,a=2