حل تشریحی سوال شماره 38 ریاضی (بوکان)

الف)

$(x+1)(x+2)=x^2+\underset{3x}{\underbrace{2x+x}}+2=x^2+3x+2$

ب)

$5\underline{ab}+3\underline{ab}c=ab(5+3c)$

ج)

$\frac{2}{3}x-\frac{1}{2}=\frac{1}{6}\Rightarrow 6\times \left(\frac{2}{3}x-\frac{1}{2}=\frac{1}{6}\right)\Rightarrow \frac{6\times 2}{3}x-\frac{6\times 1}{2}=\frac{6\times 1}{6}\Rightarrow \frac{\stackrel{2}{\cancel{6}}\times 2}{\underset{1}{\cancel{3}}}x-\frac{\stackrel{3}{\cancel{6}}\times 1}{\underset{1}{\cancel{2}}}=\frac{\stackrel{1}{\cancel{6}}\times 1}{\underset{1}{\cancel{6}}}\Rightarrow 2x-3=1\Rightarrow 2x=1+3\Rightarrow 2x=4\Rightarrow x=\frac{4}{2}\Rightarrow x=2$