Находим производную
y'=15*3x^2-18*2x
y=45*121-36*11
y=5445-396
y=5049
Y`=2cosx+2sin2x=0
2cosx(1+2sinx)=0
cosx=0⇒x=π/2∈[π/4;3π/4]
sinx=-1/2⇒x=7π/6∉[π/4;3π/4]
y(π/4)=2*√2/2-0=√2
y(π/2)=2*1+1=3 наиб
y(3π/4)=2*√2/2-0=√2
0.1×(−8)^3+0.2×(−8)^2−25=-63,4
0.1×(−8)×3+0.2×(−8)×2−25=-30.6