2 x 5 + 5 x 7 + 9 x 3
= 5 x ( 2 + 7 ) + 9 x 3
= 5 x 9 + 9 x 3
= 9 x ( 5 + 3 )
= 9 x 8
= 72
2x5+5x9+9x3 15:5+27:5+8:5
=9x5+(2+3) =(15+8+27):5
=9x5+5 =50:5
=9x5+5x1 =10
=5x(9+1) 9+9x3+18:2x6
=5x10 =1x9+9x3+9x6
=50 =9x(1+6+3)
=9x10
=90
\(15:5+27:5+8:5\)
\(=15\times\frac{1}{5}+27\times\frac{1}{5}+8\times\frac{1}{5}\)
\(=\left(15+27+8\right)\times\frac{1}{5}\)
\(=50\times\frac{1}{5}\)
\(=10\)
\(2\times5+5\times7+9\times3\)
\(=\left(2+7\right)\times5+9\times3\)
\(=9\times5+9\times3\)
\(=9\times\left(5+3\right)\)
\(=9\times8\)
\(=72\)
9 + 9 x 3 + 18 : 2 x 6
= 9 x 1 + 9 x 3 + 9 x 6
= 9 x ( 1 + 3 + 6 )
= 9 x 10
= 90
a, 2 x 5 + 5 x 7 + 9 x 3 ( có người giải r)
b, 15 : 5 + 27 : 5+ 8 : 5
= ( 15 + 27 +8 ) :5
= 50 : 5
=10
c, 9 + 9 x 3 + 18 : 2 x 6
= 3 x 3 + 9 x 3 + 9 x 3 x 2
= 3 x ( 3 + 9 + 9 x 2)
= 3 x 3 ( 1 + 3 +3 x 2)
= 9 ( 4 + 6)
= 9 x10
\(15\div5+27\div5+8\div5\)
\(=\left(15+27+8\right)\div5\)
\(=50\div5\)
\(=10\)
\(9+9\times3+18\div2\times6\)
\(=9\times1+9\times3+9\times6\)
\(=9\times\left(1+6+3\right)\)
\(=9\times10\)
\(=90\)
