Question

bài 3 tính:

a)7+ (-13) +5 + (-7) +8+(-15)

b)117 +(-32) +(-117)+(-18)

Answer 1

a) 7 + (-13) + 5 + (-7) + 8 + (-15)

= [7 + (-7)] + ( 5 + 8 ) + (-13) + (-15)

= 0 + [13 + (-13)] + (-15)

= 0 + 0 +(-15)

= -15

b) 117 + (-32) + (-117) + (-18)

= [117 + (-117)] + [(-32) + (-18)]

= 0 + (-50)

=-50

Answer 2

a , kq la -15

b , kq la -50

Answer 3

\(a,\)\(7+\left(-13\right)+5+\left(-7\right)+8+\left(-15\right)\)

\(=\left[7+\left(-7\right)\right]+\left[5+\left(-15\right)\right]+\left[8+\left(-13\right)\right]\)

\(=0\)                      \(+\)        \(\left(-10\right)\)         \(+\)        \(\left(-5\right)\)

\(=\left(-15\right)\)

\(b,\)\(117+\left(-32\right)+\left(-117\right)+\left(-18\right)\)

    \(=\left[117-\left(-117\right)\right]+\left[\left(-32\right)+\left(-18\right)\right]\)

     \(=\)          \(0\)                   \(+\)           \(\left(-50\right)\)

     \(=\left(-50\right)\)