2 - 3 2 =  2 - 3 = 2 - 3

2 3 + 2 - 3 2 = 2 3 + 2 - 3 = 2 3 + 2 - 3 = 3 + 2

3 a - 2 2   = 3 a - 2 = 3 2 - a

(vì a < 2 nên 2 – a > 0)

\(A=2\sqrt{3}+\sqrt{\left(2+\sqrt{3}\right)^2}\\ =2\sqrt{3}+\left|2+\sqrt{3}\right|\\ =2\sqrt{3}+2+\sqrt{3}\\ =3\sqrt{3}+2\)

Ta có:

Ta có:

ĐKXĐ: `x>=0;x\ne9`

`(x^2-3)/(sqrtx-3)=((x-sqrt3)(x+sqrt3))/(x+sqrt3)=x-sqrt3`

`a)(x^2-3)/(x+\sqrt3)`

`->` ĐKXĐ : `x>=0;x\ne9`

`=((x-\sqrt3)(x+\sqrt3))/(x+\sqrt3)`

`=(x-\sqrt3)/1`

`=x-\sqrt3`

d: \(D=x^3-6x^2+12x-100\)

\(=x^3-6x^2+12x-8-92\)

\(=\left(x-2\right)^3-92\)

Khi x=-98 thì \(D=\left(-98-2\right)^3-92=-1000000-92=-1000092\)

e: \(E=\left(x+1\right)^3+6\left(x+1\right)^2+12x+20\)

\(=\left(x+1\right)^3+6\left(x+1\right)^2+12\left(x+1\right)+8\)

\(=\left(x+1+2\right)^3\)

\(=\left(x+3\right)^3\)

Khi x=5 thì \(E=\left(5+3\right)^3=8^3=512\)

f: \(F=\left(2x-1\right)\left(4x^2+2x+1\right)-7\left(x^3+1\right)\)

\(=\left(2x\right)^3-1^3-7x^3-7\)

\(=x^3-8\)

Khi x=-1/2 thì \(F=\left(-\dfrac{1}{2}\right)^3-8=-\dfrac{1}{8}-8=-\dfrac{65}{8}\)

g: \(G=\left(-x-2\right)^3+\left(2x-4\right)\left(x^2+2x+4\right)-x^2\left(x-6\right)\)

\(=-\left(x+2\right)^3+2\left(x-2\right)\left(x^2+2x+4\right)-x^3+6x^2\)

\(=-x^3-6x^2-12x-8+2\left(x^3-8\right)-x^3+6x^2\)

\(=-2x^3-12x-8+2x^3-16=-12x-24\)

Khi x=-2 thì \(G=-12\cdot\left(-2\right)-24=24-24=0\)

h: \(H=\left(x-1\right)^3-\left(x+2\right)\left(x^2-2x+4\right)+3\left(x+4\right)\left(x-4\right)\)

\(=x^3-3x^2+3x-1-\left(x^3+8\right)+3\left(x^2-16\right)\)

\(=x^3-3x^2+3x-1-x^3-8+3x^2-48\)

\(=3x-57\)

Khi x=-1/2 thì \(H=3\cdot\dfrac{-1}{2}-57=-1,5-57=-58,5\)