F=-14x²+5x³ f⁾=-14*2*x+5*3*x³⁻¹=-28x+15x²
f⁾(x)<0 -28x+15x²<0<br>
-28x+15x²=0
x*(-28+15x)=0 x=0 и -28+15x=0 ⇒x=28/15
____+__0__-__28/15____+____
x∈(0; 28/15)
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f=15x²-18x+1448
f⁾(x)=15*2*x-18*1+0=30x-18
f⁾(0)=30*0-18= -18