Solve this quadratic equation by completing the square. x2 + 4x = 15

x = -2 + √19, x = -2 - √19

Step-by-step explanation:

Equation: x² + 4x = 15

Complete the square of ax² + bx: x² + 4x + 4

Insert into equation (with balancing): x² + 4x + 4 = 15 + 4

Change form: (x + 2)² = 15 + 4

Combine like terms: (x + 2)² = 19

Square root: x + 2 = ±√19

Isolate x: x = -2 ± √19

it will cost dollar $540

the living room is 3 which means if we divide 325/3 then we get $108

therefore if 1part of the living room cost $108 and 3 costed $325

then total 5part of the room will cost 5*108 which gives $540

the height of the surface increases from the center out to the sides of the road.

step-by-step explanation:

as we move out we move away from the x-axis.

and as mentioned in the problem statement that height of a road increases when we move away from the center x.

hence proved that 3rd option

the height of the surface increases from the center out to the sides of the road.

is the correct option.