(9-0.7t)(9+0.7t)

Apply the distributive property.

9(9+0.7t)-0.7t(9+0.7t)

Apply the distributive property.

9⋅9+9(0.7t)-0.7t(9+0.7t)

Apply the distributive property.

9⋅9+9(0.7t)-0.7t⋅9-0.7t(0.7t)

9⋅9+9(0.7t)-0.7t⋅9-0.7t(0.7t)

Combine the opposite terms in 9⋅9+9(0.7t)-0.7t⋅9-0.7t(0.7t).

Reorder the factors in the terms 9(0.7t) and -0.7t⋅9.

9⋅9+0.7⋅9t-0.7⋅9t-0.7t(0.7t)

Subtract 0.7⋅9t from 0.7⋅9t.

9⋅9+0⋅9t-0.7t(0.7t)

9⋅9+0⋅9t-0.7t(0.7t)

Simplify each term.

Multiply 9 by 9.

81+0⋅9t-0.7t(0.7t)

Multiply 0 by 9.

81+0t-0.7t(0.7t)

Multiply 0 by t.

81+0-0.7t(0.7t)

Multiply t by t.

81+0-0.7⋅0.7t2

Multiply -0.7 by 0.7.

81+0-0.49t2

81+0-0.49t2

Add 81 and 0.

81-0.49t2

81-0.49t2

Simplify (9-0.7t)(9+0.7t)