Which of the following expressions can be factored by grouping? (Select all that apply.) a^2 - 9 a + 7 ab + 63 b
3 a + 4 ab - b - 12
ab + 6 b - 2 a - 12
x^3 + 9 x^2 + 7 x + 63
ay^2 + a - y^2 - 1

Options (3), (4) and (5)

Step-by-step explanation:

1). a² - 9a + 7ab + 63b

  = a(a - 9) + 7b(a + 9)

  Now we can not solve this problem further.

  Therefore, can't be factored by grouping.

2). 3a + 4ab - b - 12

   = a(3 + 4b) - 1(b - 12)

   We can't solve it further.

   Therefore, can't be factored by grouping.

3). ab + 6b - 2a - 12

   = b(a + 6) - 2(a + 6)

   = (b - 2)(a + 6)

  We can be factored this expression by grouping.

4). x³ + 9x²+ 7x + 63

   = x²(x + 9) + 7(x + 9)

   = (x² + 7)(x + 9)

   Therefore, the given expression can be factored by grouping.

5). ay² + a - y² - 1

  = a(y² + 1) - 1(y² + 1)

  = (a - 1)(y² + 1)

  This expression can be factored by the grouping method.

Options (3), (4) and (5) are the correct answers.

x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x

step-by-step explanation:

last month maria hiked the 5-mile mountain trail a number of times and she hiked the 10-mile canal trail several times. let x represent the number of times she hiked the 5-mile trail, and let y represent the number of times she hiked the 10-mile trail. if she hiked a total of 90 miles, which equation can be used to find the number of times maria hiked each trail? x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x

step-by-step explanation:

what grade level is this? need to know so i can look in my old textbooks!