a: \(A=x^2+10x+25-x^2+6x-9=16x+16\)
=160+16
=176
b: \(B=x^2+2x+1-x^2+2x-1=4x=-20\)
c: \(E=x^3-3x^2+3x-1+x^3-6x^2+12x-8\)
\(=2x^3-9x^2+15x-9\)
\(=2\cdot27-9\cdot9+15\cdot3-9\)
=54-81+45-9
=9
\(a.A=\left(x+5\right)^2-\left(x-3\right)^2=x^2+10x+25-x^2+6x-9\)
\(=x^2-x^2+10x+6x+25-9=16x+16\) \(tại\) \(x=10\)
\(=16\cdot10+16=176.\)
\(b.B=\left(x+1\right)^2-\left(x-1\right)^2=x^2+2x+1-x^2+2x-1\)
\(=x^2-x^2+2x+2x+1-1=4x\) \(tại\) \(x=-5\)
\(=4\cdot\left(-5\right)=-20.\)
\(c.F=\left(x-1\right)^3+\left(x-2\right)^3\)
\(=x^3-3x^2+3x-1+x^3-6x^2+12x-8\)
\(=x^3+x^3-3x^2-6x^2+3x+12x-1-8\)
\(=2x^3-9x^2+15x-9\)\(tại\) \(x=3\)
\(=2\cdot3^3-9\cdot3^2+15\cdot3-9=2\cdot27-9\cdot9+15\cdot3-9\)
\(=54-81+45-9=9.\)
\(d.F=\left(x-1\right)^3-\left(x-2\right)^3\)
\(=x^3-3x^2+3x-1-x^3+6x^2-12x+8\)
\(=x^3-x^3-3x^2+6x^2+3x-12x-1+8\)
\(=3x^2-9x+7\) \(tại\) \(x=-2\)
\(=3\cdot\left(-2\right)-9\cdot\left(-2\right)+7=3\cdot\left(-4\right)-9\cdot\left(-2\right)+7\)
\(=-12-18+7=-23.\)
