Question

Розкрийте дужки і зведіть подібні доданки: 1) 3(7x - 2) + 5x + 21; 2) 4(3-5a) (7 - 20a);

Answer 1

Ответ:

1)26х+15

2)400а в квадраті-380а+84

Answer 2

1. 3(7x - 2) + 5x + 21

To expand the parentheses, we distribute the 3 to each term inside: 3 * 7x - 3 * 2 + 5x + 21

Simplifying further: 21x - 6 + 5x + 21

Combining like terms: (21x + 5x) + (-6 + 21)

Simplifying the coefficients and constants separately: 26x + 15

Therefore, the expression 3(7x - 2) + 5x + 21, after expanding the parentheses and combining like terms, simplifies to 26x + 15.

2. 4(3 - 5a)(7 - 20a)

To expand the expression, we apply the distributive property twice: 4 * 3 * 7 + 4 * 3 * (-20a) + 4 * (-5a) * 7 + 4 * (-5a) * (-20a)

Simplifying each term: 84 - 240a + (-140a) + 400a^2

Combining like terms: 84 + (-240a - 140a) + 400a^2

Simplifying the coefficients: 84 - 380a + 400a^2

Therefore, the expression 4(3 - 5a)(7 - 20a), after expanding the parentheses and combining like terms, simplifies to 400a^2 - 380a + 84.