Câu 1:
Ta có:
`x_0=3` `\to y_o=3^3-3.3^2=0`
`y'=3x^2-6x`
`\to y'(3)=3.3^2-6.3=9`
PTTT có dạng:
`y=y'(x_0).(x-x_0)+y_0`
`⇔ y=9(x-3)+0`
`⇔ y=9x-27`
Câu 2:
`y=cos(x^5-3x^3+2020x)`
`y'=-sin(x^5-3x^3+2020x).(x^5-3x^3+2020x)'`
`y'=-sin(x^5-3x^3+2020x).(5x^4-9x^2+2020)`