Question

31.8 (7+d)(d-7)+(d+3)(3-d)

Answer 1

Ответ:

(7+d)(d-7)+(d+3)(3-d)=(d+7)(d-7)+(3+d)(3-d)=d²-49+9-d²=-40

Answer 2

Ответ:

-40

Объяснение:

(7+d)(d-7)+(d+3)(d-3)=(d+7)(d-7)+(3+d)(3-d)=d^2-49+9-d^2=-40

Answer 3

To simplify the expression 31.8(7+d)(d-7)+(d+3)(3-d), we can begin by expanding the brackets and then combining like terms.

Expanding the first bracket: 31.8(7+d)(d-7) = 31.8 * (7 * (d-7) + d * (d-7))

Expanding the second bracket: (d+3)(3-d) = (d * 3) + (d * -d) + (3 * 3) + (3 * -d)

Now let's simplify each part separately:

Expanding the first term in the first bracket: 7 * (d - 7) = 7d - 49

Expanding the second term in the first bracket: d * (d - 7) = d^2 - 7d

Combining the terms in the first bracket: 31.8 * (7 * (d - 7) + d * (d - 7)) = 31.8 * (7d - 49 + d^2 - 7d) = 31.8 * (d^2 - 49)

Simplifying the second bracket: (d * 3) + (d * -d) + (3 * 3) + (3 * -d) = 3d - d^2 + 9 - 3d = -d^2 + 9

Now we can simplify the entire expression by combining the two terms:

31.8 * (d^2 - 49) + (-d^2 + 9) = 31.8d^2 - 1594.2 - d^2 + 9

Combining like terms:

(31.8d^2 - d^2) - 1594.2 + 9 = 30.8d^2 - 1585.2

Therefore, the simplified expression is 30.8d^2 - 1585.2.