y=asinx+(5+2x)cosx Differential w.r.t '
x '
y′=acosx+(5+2x)(−sinx)+(0+2)cosxy′=acosx−(5+2x)sinx+2cosx Again differential w.r.t '
x '
y′′=−asinx−[(5+2x)cosx+(0+2)sinx]+2(−sinx)⇒y′′=−asinx−(5+2x)cosx−2sinx−2sinx⇒y′′=−(asinx+(5+2x)cosx)−4sinx⇒y′′=−y−4sinx⇒y′′+y=−4sinx