Tính = 2 cách :
a) 15 x 12 – 35 x 10
b) 45 – 9 x (13 + 5 )
c) 29 x ( 19 – 13 ) – 19 x ( 29 – 13 )
Tính = 2 cách : a) 15 x 12 – 35 x 10 b) 45 – 9 x (13 + 5 ) c) 29 x ( 19 – 13 ) – 19 x ( 29 – 13 )
By Parker
By Parker
Tính = 2 cách :
a) 15 x 12 – 35 x 10
b) 45 – 9 x (13 + 5 )
c) 29 x ( 19 – 13 ) – 19 x ( 29 – 13 )
Đáp án:
$\begin{array}{l}
a)\\
c1:15 \times 12 – 35 \times 10 = 180 – 350 = – 170\\
c2:15 \times 12 – 35 \times 10\\
= 3 \times 5 \times 2 \times 6 – 35 \times 10\\
= 18 \times 10 – 35 \times 10\\
= 10 \times \left( {18 – 35} \right)\\
= 10 \times \left( { – 17} \right)\\
= – 170\\
b)\\
c1:45 – 9 \times \left( {13 + 5} \right)\\
= 45 – 9 \times 18\\
= 45 – 162\\
= – 117\\
c2:45 – 9 \times \left( {13 + 5} \right)\\
= 9 \times 5 – 9 \times 18\\
= 9 \times \left( {5 – 18} \right)\\
= 9 \times \left( { – 13} \right)\\
= – 117\\
c)\\
c1:29 \times \left( {19 – 13} \right) – 19 \times \left( {29 – 13} \right)\\
= 29 \times 6 – 19 \times 16\\
= 174 – 304\\
= – 130\\
c2:29 \times \left( {19 – 13} \right) – 19 \times \left( {29 – 13} \right)\\
= 29 \times 19 – 29 \times 13 – 19 \times 29 + 19 \times 13\\
= 13 \times \left( { – 29 + 19} \right)\\
= 13 \times \left( { – 10} \right)\\
= – 130
\end{array}$
`a)C1:` `15 × 12 – 35 × 10`
`= 180 – 350`
`= -170`
`C2:` `15 × 12 – 35 × 10`
`= 3 × 5 × 2 × 6 – 35 × 10`
`= 18 × 10 – 35 × 10`
`= 10 × (18 – 35)`
`= 10 × (- 17)`
`= -170`