Question

If 2x-1=13, evaluate the expression -x^2-4x.

Answer 1

- 77

Explanation:

The given expression is -x^2-4x; there is another expression (2x - 1 = 13), which can be solved for x as follows:

2x - 1 = 13

Adding 1 to both sides, we get:

2x = 14

Dividing both sides by 2 results in: x = 7

Substituting 7 for x in -x^2-4x yields -(7)^2-4(7), or:

-49 - 28, or -77

Answer 2

-77

Explanation:

2x-1=13

2x=13+1=14

x=14/2=7

`-x^2-4x=-(7)^2-4(7)=-49-28=-77`