(1,0 điểm) Tính hợp lí biểu thức sau: a) − 4 2 + { − 54 : [ ( − 2 ) 3 + 7 ⋅ 2 ] } . b) 87 ⋅ ( 13 − 45 ) − 13 ⋅ ( 87 + 45 ) .

a) \[ - {4^2} + \left\{ { - 54:\left[ {{{\left( { - 2} \right)}^3} + 7 \cdot 2} \right]} \right\}\]

\( = - 16 + \left\{ { - 54:\left[ { - 8 + 14} \right]} \right\}\)

\( = - 16 + \left\{ { - 54:6} \right\}\)

\( = - 16 + \left( { - 9} \right)\)

\( = - 25.\)

b) \[87 \cdot \left( {13 - 45} \right) - 13 \cdot \left( {87 + 45} \right)\]

\[ = 87 \cdot 13 - 87 \cdot 45 - 13 \cdot 87 - 13 \cdot 45\]

\[ = \left( {87 \cdot 13 - 13 \cdot 87} \right) - \left( {87 \cdot 45 + 13 \cdot 45} \right)\]

\[ = - 45 \cdot \left( {87 + 13} \right)\]

\[ = - 45 \cdot 100\]

\( = - 4\,\,500.\)