Przypomnijmy wzory skróconego mnożenia na kwadrat sumy i różnicy:

${\left(a+b\right)}^2=a^2+2ab+b^2$  

${\left(a-b\right)}^2=a^2-2ab+b^2$  

 

a)

${\left(x-10\right)}^2=x^2-2\cdot x\cdot 10+{10}^2=x^2-20x+100$  

 

b)

${\left(9+x\right)}^2=9^2+2\cdot 9\cdot x+x^2=81+18x+x^2$  

 

c)

${\left(x-\frac{1}{4}\right)}^2=x^2-2\cdot x\cdot \frac{1}{4}+{\left(\frac{1}{4}\right)}^2=x^2-\frac{1}{2}x+\frac{1}{16}$  

 

d)

${\left(x+\frac{2}{5}\right)}^2=x^2+2\cdot x\cdot \frac{2}{5}+{\left(\frac{2}{5}\right)}^2=x^2+\frac{4}{5}x+\frac{4}{25}$  

 

e)

${\left(3x+8\right)}^2={\left(3x\right)}^2+2\cdot 3x\cdot 8+8^2=9x^2+48x+64$  

 

f)

${\left(0,5x+2\right)}^2={\left(0,5x\right)}^2+2\cdot 0,5x\cdot 2+2^2=0,25x^2+2x+4$  

 

g)

${\left(4x-0,2\right)}^2={\left(4x\right)}^2-2\cdot 4x\cdot 0,2+{0,2}^2=16x^2-1,6x+0,04$  

 

h)

${\left(6x-\frac{1}{2}\right)}^2={\left(6x\right)}^2-2\cdot 6x\cdot \frac{1}{2}+{\left(\frac{1}{2}\right)}^2=36x^2-6x+\frac{1}{4}$