SOLUTION: Solve: a) x2 - 6x - 16 = 0 b) 6x2 + 42 = 0 f(t) = 2t2 - 4t - 1 find a) f(2) b) f(-1)

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: Solve: a) x2 - 6x - 16 = 0 b) 6x2 + 42 = 0 f(t) = 2t2 - 4t - 1 find a) f(2) b) f(-1)      Log On


   

Question 204727: Solve:
a) x2 - 6x - 16 = 0
b) 6x2 + 42 = 0
f(t) = 2t2 - 4t - 1 find
a) f(2)
b) f(-1)
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
a) Solve:
x%5E2-6x-16+=+0 Factor the trinomial.
%28x%2B2%29%28x-8%29+=+0 so that...
x%2B2+=+0 or x-8+=+0 therefore...
highlight%28x+=+-2%29 or highlight_green%28x+=+8%29
b) 6x%5E2%2B42+=+0 Subtract 42 from both sides of the equation.
6x%5E2+=+-42 Divide both sides by 6.
x%5E2+=+-7 Take the square root of both sides.
highlight%28x+=+sqrt%28-7%29%29 or highlight_green%28x+=+-sqrt%28-7%29%29
c) f%28t%29+=+2t%5E2-4t-1
Find:
f%282%29 Simply substitute t = 2 into the equation and simplify.
f%282%29+=+2%282%29%5E2-4%282%29-1 Evaluate.
f%282%29+=+2%284%29-8-1
f%282%29+=+8-8-1
highlight%28f%282%29+=+-1%29
f%28t%29+=+2t%5E2-4t-1 Substitute t = -1
You should be able to handle this one using the previous one as a guide!