Question

State which is greater:
(i) $(8+9)\times 10$ and $8+9\times 10$
(ii) $(8-9)\times 10$ and $8-9\times 10$
(iii) $\left\{\right(-2)-5\}\times (-6)$ and $(-2)-5\times (-6)$

Answer 1

(i) $(8+9)\times 10=17\times 10=170$

$8+9\times 10=8+90=98$

$170>98$

$\therefore (8+9)\times 10>8+9\times 10$
(ii) $(8-9)\times 10=(-1)\times 10=-10$

$8-9\times 10=8-90=-82$

$-10>-82$

$\therefore (8-9)\times 10>8-9\times 10$
(iii) $\left\{\right(-2)-5\}\times (-6)=-7\times (-6)=42$

$(-2)-5\times (-6)=(-2)-(5\times -6)=(-2)-(-30)=-2+30=28$

$42>28$

$\therefore \left\{\right(-2)-5\}\times (-6)>(-2)-5\times (-6)$