Question

Найди значение выражения: (6c−9d)⋅(6c+9d)−36c2,
если c=3 и d=0,1

Answer 1

$36 {c}^{2} - 81 {d}^{2} - 36 {c}^{2} = - 81 {d}^{2} = - 81 times (0.1 {)}^{2} = - 81 times 0.01 = - 0.81$

Answer 2

(36c²-81d²)-36c² = 36×3²-81×0.1²-36×3² = 324-0.81-324 = -0.81