Đáp án:
Giải thích các bước giải:
a) $253\times 75-161\times 37+253\times 25-\frac{161\times 63}{100}\times 47-12\times \frac{7}{2}-5,8\div \frac{1}{10}\\=253\times 100-161(\frac{63}{100}\times 47+37)-42-58\\=25300-161(\frac{2961}{100}+37)-100\\=25337-161\times \frac{6661}{100}-100\\=25337-10724,21-100\\=14475,79$
b) $28+62\times a\times (a\times a-a\div 1)+28\times 8+28\\=28\times 10+62a(a^2-a)\\=62a^3-62a^2+280$