Question

(0,8а+0,3b)*(0,6b-1,2a)
Если а=2 1/12, b= - 1 1/9.
Помогите плииз

Answer 1

Ответ:

Пошаговое объяснение:

$(0.8a+0.3b)(0.6b-1.2a)=0.48ab+0.18b^2-0.96a^2-0.36ab=0.18b^2+0.12ab-0.96a^2$

$0.18*(-\frac{10}{9} )^2=0.18*\frac{100}{81} =\frac{18}{100} *\frac{100}{81} =\frac{18}{81}$

$\frac{12}{100} *\frac{25}{12} =\frac{25}{100} *(-\frac{10}{9} )=-\frac{25}{90}$

$0.96*(\frac{25}{12} )^2=\frac{96}{100} *\frac{625}{144} =\frac{200}{48}$

$\frac{18}{81} -\frac{25}{90} =\frac{180}{810} -\frac{225}{810} =-\frac{45}{810}$

$-\frac{45}{810} -\frac{200}{48} =-\frac{360}{6480} -\frac{27000}{6480} =-\frac{27360}{6480} -\frac{2736}{648} =-\frac{38}{9} =-4\frac{2}{9}$