A is right , using the exponet property, it turns into to the 7 power which equal x to the 1.4 th power. Using the product of power, to the 7th power is the same as 1/5 times 7 which equal 1.4. so b is right .Using the fractioal exponet rule C is also right as 5th root of x to the 7th power is the same as to the 7 power divided by 5 which 1.4 so c is right
