Tính: a) 2. 6 .(– 6 ) = ……………………………………………………………

b) $\sqrt{\mathrm{1,44}}-2.{\left(\sqrt{\mathrm{0,6}}\right)}^2$ = 1,2 – 2 . 0,6 = 1,2 – 1,2 = 0.

c) 0,1. ${\left(\sqrt{7}\right)}^2$ + $\sqrt{\mathrm{1,69}}$ = 0,1 . 7 + 1,3 = 0,7 + 1,3 = 2.

d) (–0,1). ${\left(\sqrt{120}\right)}^2$ – $\frac{1}{4}.{\left(\sqrt{20}\right)}^2$ = –0,1 . 120 – $\frac{1}{4}$. 20 = –12 – 5 = –17.

a)

$\sqrt{x}$– 16 = 0

$\sqrt{x}$= 16

${\left(\sqrt{x}\right)}^2$= 16²

x = 256.

b)

2. $\sqrt{x}$ = 1,5

$\sqrt{x}$ = 0,75

${\left(\sqrt{x}\right)}^2$ = $0,{75}^2$

x = 0,5625.