tính bằng cách thuận tiện nhất : a) 1/12 + 3/16 + 5/12 + 5/16 , b) 7/15 + 9/16 + 8/15 + 7/16 , c) 5/2 x 3/2 + 17/2 x 3/2 + 3/2 , d) 3 x 7/10 + 7/10 x 5 + 2 x 7/10 các bạn trình bày đầy đủ nha .
tính bằng cách thuận tiện nhất : a) 1/12 + 3/16 + 5/12 + 5/16 , b) 7/15 + 9/16 + 8/15 + 7/16 , c) 5/2 x 3/2 + 17/2 x 3/2 + 3/2 , d) 3 x 7/10 + 7/10 x
By Autumn
`a)` ` 1/12 + 3/16 + 5/12 + 5/16`
`=(1/12+5/12)+(3/16+5/16)`
`=1/2+1/2`
`=2/2`
`=1`
`b)` ` 7/15 + 9/16 + 8/15 + 7/16`
`=(7/15+8/15)+(9/16+7/16)`
`=15/15+16/16`
`=1+1`
`=2`
`c)` ` 5/2 × 3/2 + 17/2 × 3/2 + 3/2 `
`=3/2×(5/2+17/2+1)`
`=3/2×12`
`=36/2`
`=18`
`d) ` `3 × 7/10 + 7/10 ×5 + 2 × 7/10`
`=7/10×(3+5+2)`
`=7/10×10`
`=70/10`
`=7`