c) Ta có: \(C=7\left(x-8\right)^2-9\left(x+3\right)^2+50\)
\(=7\left(x^2-16x+64\right)-9\left(x^2+6x+9\right)+50\)
\(=7x^2-112x+448-9x^2-54x-81+50\)
\(=-2x^2-166x-31\)
\(=-2\cdot\dfrac{1}{49}-166\cdot\dfrac{-1}{7}-31\)
\(=\dfrac{-359}{49}\)
g) Ta có: \(G=x^{17}-3x^{16}+3x^{15}-3x^{14}+...+3x\)
\(=x^{17}-x^{16}\left(x+1\right)+x^{15}\left(x+1\right)-x^{14}\left(x+1\right)+...+x\left(x+1\right)\)
\(=x^{17}-x^{17}-x^{16}+x^{16}+x^{15}-x^{15}-x^{14}+...+x^2+x\)
=x
=2
Đúng 2
Bình luận (0)
