2007-03-18 08:15:00 · 2 answers · asked by snclove2001 1 in Education & Reference ➔ Homework Help
Let b be the length of the base. Then the height is 5 less than the base, or b-5. Plug this into the formula for the area of a triangle:
A = 1/2 (b) (h)
42 = 1/2 (b) (b-5) (substitute in)
42 = 1/2 (b^2 - 5b) (Distribute the b)
84 = b^2 - 5b (multiply both sides by 2)
b^2 - 5b - 84 = 0 (get everything to one side, then factor)
(b-12)(b+7)=0
b = 12 or b = -7 (set each factor equal to zero, then solve).
Since a negative base doesn't make sense, we can disregard the -7 answer, and say that the base is 12 units (inches, in this case).
2007-03-18 08:20:19 · answer #1 · answered by Mr. Adkins 4 · 0⤊ 0⤋
next time post this in science & mathematics, you'll get answers quicker
42=.5(x)(x-5)
84=x^2-5x
x^2-5x-84=0
(x-12)(x+7)=0
x=12 (it can't be -7)
2007-03-18 15:21:07 · answer #2 · answered by bksrbttr 3 · 0⤊ 0⤋