Question

a) Tính GTBT: A=x⁵-36x⁴+37x³-69x²-34x+15 tại x=35.

b) Tìm x: 3(6x-5)(4x+1)-(8x+3)(9x-2) =203

Answer 1

a)\(A=x^5-36x^4+37x^3-69x^2+34x+15\)

=\(x^5-35x^4-x^4+35x^3+2x^2-70x^2+x^2-35x+x+15\)

=\(\left(x^4-x^3+x^2+x\right)\left(x-35\right)+x+15\)

=0+35+15=50(do x=35)

Answer 2

b, \(3\left(6x-5\right)\left(4x+1\right)-\left(8x+3\right)\left(9x-2\right)=203\)

\(\Rightarrow3\left(24x^2+6x-20x-5\right)-\left(72x^2-16x+27x-6\right)=203\)

\(\Rightarrow72x^2-42x-15-72x^2-11x+6=203\)

\(\Rightarrow-53x=203-6+15=212\)

\(\Rightarrow x=-4\)

Chúc bạn học tốt!!!