حل تشریحی سوال شماره 151 ریاضی (اردبیل - پارس آباد)

الف)

$8-4(3\times 2^2)÷2+1=8-4(3\times 4)÷2+1=8-48÷2+1=8-24+1=-15$

ب)

$\left(-\frac{5}{7}+\frac{1}{21}\right)÷\left(-\frac{14}{42}\right)=\left(-\frac{15}{21}+\frac{1}{21}\right)÷\left(-\frac{14}{42}\right)=\left(-\frac{14}{21}\right)÷\left(-\frac{14}{42}\right)=\left(-\frac{14}{21}\right)\times \left(-\frac{42}{14}\right)=2$