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The roots of 7x^2 + x - 5 = 0 are a and b. Compute (a + 4)(b + 4)/(ab).

 May 31, 2021

Best Answer 

 #1
avatar+62 
+3

Answer:

15 6/7

Explanation:

The roots of 7x^2 + x - 5 = 0 are a and b.

Compute (a - 4)(b - 4).

 

Use of this information:

For the quadratic equation ax^2+bx+c=0, the sum of its roots = –b/a and the product of its roots = c/a.

In given case:

sum of roots=a+b= - 1/7

product of roots=ab= -5/7

Now let's find the value of (a-4)(b-4)

(a-4)(b-4)=

ab-4(a+b)+16=

-5/7-4(-1/7)+16=

-1/7+16=

15 6/7

The answer is 15 6/7

 

👍🏻👍🏻👍🏻

 May 31, 2021
 #1
avatar+62 
+3
Best Answer

Answer:

15 6/7

Explanation:

The roots of 7x^2 + x - 5 = 0 are a and b.

Compute (a - 4)(b - 4).

 

Use of this information:

For the quadratic equation ax^2+bx+c=0, the sum of its roots = –b/a and the product of its roots = c/a.

In given case:

sum of roots=a+b= - 1/7

product of roots=ab= -5/7

Now let's find the value of (a-4)(b-4)

(a-4)(b-4)=

ab-4(a+b)+16=

-5/7-4(-1/7)+16=

-1/7+16=

15 6/7

The answer is 15 6/7

 

👍🏻👍🏻👍🏻

Derekshakk May 31, 2021

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