graphing a linear equation

Question

bethany has 1,200 in her checking account. She deposits 1,850 per month and spends 2,000 per month.  if you graph this after writing a linear equation what would the slope of the graph represent and the yintercept and the x intercept  i really dont understand this at all

Answer 1

• Your equation her would be Y=1200+1850X-2000X, or Y=1200-150X
• Y=her account balance
• X=number of months

 

I got this equation by adding her deposits (1850*X) and subtracting her spending (200*X).  This is in standard slope intercept form, which might be easier to see if I reverse the two pieces.

 

• Y=mx+b
• Y=-150X+1200

 

• Here the y intercept is the 1200, which indicates her starting balance.  (Y intercepts are often your initial conditions)
• The slope is -150, which represents the rate at which her balance is changing.  Note in this case, it's a negative number, so her balance is decreasing each month bv $150.
  
• The x intercept is the point where y is zero, which we can solve for.
• 0=-150X+1200
• 150X=1200
• X=8
• This x intercept of X=8 is the point when her balance will be 0.  She will deplete her account in 8 months.