Question

bài 8

f(x)=x^3-x^2+5

g(x) =-2x^3 +x^2 +2x +1

a)f(x) +g(x)

f(x)-g(x)

b) tìm h(x)= 2f(x)-g(x)

Answer 1

a. \(f\left(x\right)+g\left(x\right)=\left(x^3-x^2+5\right)+\left(-2x^3+x^2+2x+1\right)\)

\(=x^3-x^2+5-2x^3+x^2+2x+1\)

\(=-x^3+2x+6\)

\(f\left(x\right)-g\left(x\right)=\left(x^3-x^2+5\right)-\left(-2x^3+x^2+2x+1\right)\)

\(=x^3-x^2+5+2x^3-x^2-2x-1\)

\(=3x^3-2x^2-2x+4\)

b. Ta co

\(2f\left(x\right)=2.\left(x^3-x^2+5\right)=2x^3-2x^2+10\)

\(2f\left(x\right)-g\left(x\right)=2x^3-2x^2+10-\left(-2x^3+x^2+2x+1\right)\)

\(=2x^3-2x^2+10+2x^3-x^2-2x-1\)

\(=4x^3-3x^2-2x+9\)

tick nha