ACT Geometry Slope Intercept Form of a Line Chegg Test Prep

have you ever looked at tough math problem and asked yourself when am ever going to use this well have good news for you you can use it on the ACT okay let's talk about the slope intercept formula the equation we'll use is = mx + where is the y-coordinate is the slope is the coordinate and is the intercept but what fun is knowing all this if we can't apply it to problem let's look at an example which of the following is the graph of the equation 4x + 2 = 6 in the standard XY coordinate plane the answer choices show graphs of our equation to find the slope and intercept we first need to convert the equation into the = mx + format which means me we need to do little algebra first we subtract 4X from each side then we divide each side by 2 to get = -2x + 3 remember that the slope is the coefficient of or what is multiplied by in this case the slope is -2 and the intercept is three the number that's alone let's go back to our answer choices the intercept of line is easy to identify on graph so let's eliminate the answer choices that don't have intercept of three since the slope is -2 we can eliminate any choice where the line moves upward so we can eliminate we're left with which is our answer Circle it equal mx + is very useful formula but there's one rule about lines that we should cover try this on for size every point on line must work in the equation of line even if the equation isn't in intercept form what does that even mean let's look at problem and get to the bottom of this which of the following points does not lie on the line determined by the equation + 3 = -12 the answer choices show coordinates let's first Circle does not lie so we don't mistakenly look for points that do lie on the line since every point on line must work in the equation + 3 = -12 let's look at each of the answer choices to see which one will not work in the equation let's start with Choice 0 -4 plugging 0 in for and -4 in for we get -12 = -12 that's point on the line but we're looking for point that is not on the line so we can eliminate answer Choice now let's look at plug 2 into the equation for and plug -3 in for 2 - 9 or -7 doesn't equal -12 since we're looking for the point that does not lie on the line is the correct answer it's not necessary to look at the other answer choices but if you like to check you can plug them all into the equation and you'll see they're all on the line so answer Choice it is nice work so there you have it by applying the slope intercept formula you can find the slope and intercept of line and you can identify line based on that knowledge see told you this formula would come in handy