Question

Выберите неверное равенство: А.(3b-c)(3b+c)=9b²-c²; B.(x+4)(4-x)=16-x²; C.36n²-49=(6n+7)(7-6n) D.y⁴-25=(y²-5)(y²+5) 4 И решение пожалуйста

Answer 1

С.(6n+7)(7-6n)=42n-36n2+49-42n=49-36n2.

Answer 2

Incorrect Equation:

The incorrect equation is C. 36n²-49=(6n+7)(7-6n).

Let's go through each equation to verify this:

A. (3b-c)(3b+c)=9b²-c²: This equation is correct. It follows the formula for the difference of squares, where (a-b)(a+b) = a² - b². In this case, a = 3b and b = c, so the equation becomes (3b-c)(3b+c) = (3b)² - c² = 9b² - c².

B. (x+4)(4-x)=16-x²: This equation is correct. It also follows the formula for the difference of squares. In this case, a = x+4 and b = 4-x, so the equation becomes (x+4)(4-x) = (x+4)² - (4-x)² = (x+4)² - (4-x)² = 16 - x².

C. 36n²-49=(6n+7)(7-6n): This equation is incorrect. It does not follow the formula for the difference of squares. If we expand the right side of the equation, we get (6n+7)(7-6n) = 42n - 36n² + 49 - 42n = 49 - 36n². Therefore, the correct equation should be 49 - 36n², not 36n² - 49.

D. y⁴-25=(y²-5)(y²+5)+4: This equation is correct. It follows the formula for the difference of squares. In this case, a = y²-5 and b = y²+5, so the equation becomes (y²-5)(y²+5) = (y²-5)² - (y²+5)² = y⁴ - 25.

Therefore, the incorrect equation is C. 36n²-49=(6n+7)(7-6n).

Let me know if you have any further questions!