Question

Question :-

Subtract b(b² + 2b − 7) − 5 from 5b² − 8 and find the value of the expression obtained for b = – 3.

Answer 1

QuestioN :

Subtract b(b² + 2b − 7) − 5 from 5b² − 8 and find the value of the expression obtained for b = – 3.

GiveN :

• Subtract b(b² + 2b − 7) − 5 from 5b² − 8
• b = – 3.

To FiNd :

• The value of the expression

ANswer :

The value of the expression is b = $\frac{17}{5}$

SolutioN :

5b² - 8 - b(b² + 2b − 7) - 5 =  b - 3

5b² - 8 - 2b² + 2b - 7 - 5 = b - 3

5b² - 2b² + 2b - 8 - 7 - 5 = b - 3

3b² + 2b - 8 - 7 - 5 = b - 3

5b³ - 20 = b - 3

5b² = b - 3 + 20

5b² = b - 17

$\frac{5b^2}{b} = 17$

5b = 17

b = $\frac{17}{5}$

∴Hence, the value of the expression is b = $\frac{17}{5}$

Answer 2

Answer:

b = 17/5

Step-by-step explanation:

5b² - 8 - b(b² + 2b − 7) - 5 =  b - 3

5b² - 8 - 2b² + 2b - 7 - 5 = b - 3

5b² - 2b² + 2b - 8 - 7 - 5 = b - 3

3b² + 2b - 8 - 7 - 5 = b - 3

5b³ - 20 = b - 3

5b² = b - 3 + 20

5b² = b - 17

5b² - 8 - b(b² + 2b − 7) - 5 =  b - 3

5b² - 8 - 2b² + 2b - 7 - 5 = b - 3

5b² - 2b² + 2b - 8 - 7 - 5 = b - 3

3b² + 2b - 8 - 7 - 5 = b - 3

5b³ - 20 = b - 3

5b² = b - 3 + 20

5b²/b = 17

5b = 17

b = 17/5