4. Thực hiện phép tính : a) (6²⁰⁰⁷-6²⁰⁰⁶):6²⁰⁰⁶ b) (5²⁰⁰¹-5²⁰⁰⁰):5²⁰⁰⁰ c) (7²⁰⁰⁵+7²⁰⁰⁴):7²⁰⁰⁴ d) (5⁷+7⁵).(6⁸+8⁶).(2⁴-4²) e) (7⁵+7⁹).(5⁴+5⁶).(3³.3-9²)

Đáp án:

a) $5$

b) $4$

c) $6$ 

d) $0$

e) $0$

f) $682$ 

Giải thích các bước giải:

a) $\dfrac{6^{2007}-6^{2006}}{6^{2006}}$
$= \dfrac{6^{2007}}{6^{2006}}-\dfrac{6^{2006}}{6^{2006}}$
$= 6-1= 5$ 

b) $\dfrac{5^{2001}-5^{2000}}{5^{2000}}$
$= \dfrac{5^{2001}}{5^{2000}}-\dfrac{5^{2000}}{5^{2000}}$
$= 5-1= 4$ 

c) $\dfrac{7^{2005}-7^{2004}}{7^{2004}}$
$= 7-1= 6$ 

d) $\left ( 5^{7}+7^{5} \right )\left ( 6^{8}+8^{6} \right )\left ( 2^{4}-4^{2} \right )$
$= \left ( 5^{7}+7^{5} \right )\left ( 6^{8}+8^{6} \right ).0$
$= 0$ 

e) $\left ( 7^{5}+7^{9} \right ) \left ( 5^{4}+5^{8} \right )\left ( 3^{3}.3-9^{2} \right )$
$= \left ( 7^{5}+7^{9} \right )\left ( 5^{4}+5^{8} \right ).0$
$= 0$ 

f) $\left [ 5^{2}.2^{3}-\dfrac{7^{2}.2}{2} \right ].6-7.2^{5}$
$= \left [ 25.8-49 \right ].6-7.32$
$= 151.6-224= 682$