document.write( "Question 450936: I am having a hard time figuring out (a).. I have no idea how to set it up and solve- any help would be much appreciated!!!!\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "In 2004, there were an estimated 39 million HIV infections worldwide with an annual infection rate of 4.9 million.\r
\n" ); document.write( "\n" ); document.write( "
\n" ); document.write( "a. Find the slope intersect form of a line that approximates the cumulative number of HIV infections in million during year X, where X ≥ 2004.\r
\n" ); document.write( "\n" ); document.write( "b. Estimate the number of HIV infections in 2010. \n" ); document.write( "
Algebra.Com's Answer #310102 by jorel1380(3719)\"\" \"About 
You can put this solution on YOUR website!
y=39*10^7+4.9*10^7x
\n" ); document.write( "If you want to graph it in millions:
\n" ); document.write( "y=4.9x+39
\n" ); document.write( "\"graph%28400%2C600%2C-80%2C80%2C-80%2C80%2C4.9x%2B39%29\"
\n" ); document.write( "\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "\n" ); document.write( "
Solved by pluggable solver: DESCRIBE a linear EQUATION: slope, intercepts, etc
Equation \"-4.9+x+%2B+1+y+=+39\" describes a sloping line. For any
\n" ); document.write( " equation ax+by+c = 0, slope is \"-a%2Fb+=+--4.9%2F1\".
  • X intercept is found by setting y to 0: ax+by=c becomes ax=c. that means that x = c/a. 39/-4.9 = -7.95918367346939.
  • Y intercept is found by setting x to 0: the equation becomes by=c, and therefore y = c/b. Y intercept is 39/1 = 39.
  • Slope is --4.9/1 = 4.9.
  • Equation in slope-intercept form: y=4.9*x+39.
\n" ); document.write( "
\n" ); document.write( " \n" ); document.write( "
\n" );