Answer:
7 d/dx[x^4]
Step-by-step explanation:
Since 7 is constant with respect to x, the derivative of 7x^4 with respect to x is 7 d/dc [x^4]
8(11 + 2r) = 126r + 3
first open the parenthesis
88 + 16r = 126r + 3
88 - 3 = 126r - 16 r
85 = 110r
divide both-side of the equation by 110
85/110 = r
r= 17/22
cosC = BC/AC