Question

A triangle has a base length of (2x - 4) units and a height of (x + 5) units. Write and solve a quadratic equation to determine what value of x gives the triangle an area of 44 square units.

Answer 1

x=6

Explanation:

The area of a triangle is given by

A = 1/2 bh

44 = 1/2 (2x-4)(x+5)

Multiply the 1/2 time (2x-4)

44 = (x-2) (x+5)

FOIL

44 = x^2 +5x -2x-10

Combine like terms

44 = x^2 +3x -10

Subtract 44 from each side

0 = x^2 +3x -10-44

0 = x^2 +3x -54

Factor

What two numbers multiply to -54 and add to 3

9*-6 = -54

9+-6 = -3

0 = (x+9)(x-6)

Using the zero product property

x +9 =0 x-6 =0

x = -9 x = 6

The height cannot be negative so x cannot be -9

x=6