a)(x-3y)(x^2+3xy+9y^2)

b)(x^2-3)(x^4+3x^2+9)

c)(x+2y+z)(x+2-z)

d)(2x-1)*(4x^2 +2x+1)

e) (5+3x)^3

CMR: x^2 - 3x + 2 > 0 với mọi x

Tính nhanh:

a) $201^2$

b) $99^2$

c) 48.52

d) $32^2+68^2+68.64$

e) $86^2+36^2-72.86$

CMR: x^2 - 10x + 30 > 0 với mọi x

cmr A=n3(n2-7)2-36n chia hết cho 5040

Cho : a+2b+3c=0

a2+4b2+9c2=20

Tính : a4+16b4+81c4

Cho a + b + c = 0

CM: a^3 + b^3 + c^3 = 3abc

Tính nhanh :

978^2+22^2+978*44

Tính :

x^2+6x+9 với x=997

16a2+25b2+40ab

giải pt sau

g) 11+8x-3=5x-3+x

h)4-2x+15=9x+4-2x

g)$\dfrac{3x+2}{2}-\dfrac{3x+1}{6}=\dfrac{5}{3}+2x$

h)$\dfrac{x+4}{5}-x+4=\dfrac{4x+2}{5}-5$

i)$\dfrac{4x+3}{5}-\dfrac{6x-2}{7}=\dfrac{5x+4}{3}+3$

k) $\dfrac{5x+2}{6}-\dfrac{8x-1}{3}=\dfrac{4x+2}{5}-5$

m) $\dfrac{2x-1}{5}-\dfrac{x-2}{3}=\dfrac{xx+7}{15}$

n)$\dfrac{1}{4}\left(x+3\right)=3-\dfrac{1}{2}\left(x+1\right)-\dfrac{1}{3}\left(x+2\right)$

p)$\dfrac{x}{3}-\dfrac{2x+1}{6}=\dfrac{x}{6}-x$

q)$\dfrac{2+x}{5}-0,5x=\dfrac{1-2x}{4}+0,25$