Question

(b+6)(b-6)-b(b+5) при b= -3/5​

Answer 1

(b+6)(b-6)-b(b+5)=b²-36-b²-5b=-36-5b=-36-5•(-⅗)=

=-36+3=-33

Answer 2

To evaluate the expression (b+6)(b-6)-b(b+5) when b = -3/5, we substitute -3/5 for b in the expression and simplify.

Let's calculate step by step:

1. Substitute b = -3/5 in (b+6)(b-6): (-3/5 + 6)(-3/5 - 6)

2. Simplify the expression: (-3/5 + 6) = (6 - 3/5) (30/5 - 3/5) = 27/5

   (-3/5 - 6) = (-3/5 - 30/5) (-33/5)

3. Substitute b = -3/5 in b(b+5): (-3/5)(-3/5 + 5)

4. Simplify the expression: (-3/5)(-3/5 + 25/5) (-3/5)(22/5) = -66/25

5. Subtract the result of step 4 from the result of step 2: 27/5 - (-66/25)

6. To subtract fractions, we need a common denominator. The least common multiple of 5 and 25 is 25. Therefore, we convert the fractions to have a denominator of 25: 27/5 = (27/5) * (5/5) = 135/25 (-66/25) = (-66/25) * (1/1) = -66/25

7. Subtract the fractions: 135/25 - (-66/25) = 135/25 + 66/25 = 201/25

So, when b = -3/5, the expression (b+6)(b-6)-b(b+5) evaluates to 201/25.