a, C = x . $\frac{5}{7}$ – x + $\frac{1}{8}$ khi | x | = $\frac{1}{2}$
b, D = $\frac{3}{7}$ . x + $\frac{8}{3}$ – x khi | x | = 6
a, C = x . $\frac{5}{7}$ – x + $\frac{1}{8}$ khi | x | = $\frac{1}{2}$ b, D = $\frac{3}{7}$ . x + $\frac{8}{3}$ – x khi | x | = 6
By Valentina
Thay `x = 1/2` vào biểu thức, ta có :
`1/2 . 5/7 – 1/2 + 1/8`
`= 5/14 – 1/2 + 1/8`
`= 5/14 – 7/14 + 1/8`
`= -2/14 + 1/8`
`= -1/7 + 1/8`
`= -8/56 + 7/56`
`= -1/56`
Thay `x = 6` vào biểu thức, ta có :
`3/7 . 6 + 8/3 – 6`
`= 18/7 + 8/3 – 6`
`= 54/21 + 56/21 – 6`
`= 110/21 – 126/21`
`= -16/21`