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Writing linear equations. 5.1 and 5.2. Writing a linear equation given the slope and y-intercept. Use the equation y = mx + b The slope is the m in the equation. The b is the y-intercept in the equation.
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Writing linear equations 5.1 and 5.2
Writing a linear equation given the slope and y-intercept • Use the equation y = mx + b • The slope is the m in the equation. • The b is the y-intercept in the equation. • The equation of your line should be in the form y = #x + # where you have filled in for the missing #’s Slope = 5 and the y-intercept = -3 y = 5x - 3 slope y-intercept
Writing a linear equation given a point and the slope. • Use the equation y = mx + b • The slope is your m in the equation. • The point is your x and y in y = mx + b. • The only part of the equation that you do not know is b, so you must find it. • Substitute in x, y, and m into y = mx + b and solve for b. • After finding b, go back to y = mx + b and substitute in the value of b and the slope. (4,5), slope = Substitute in m and b y = x + 4 5 = (4) + b 5 = 1 + b -1 -1 m b 4 = b
Writing a Linear equation with two points • Find the slope of the line with the slope equation • Find the b value by picking one of the given points and substituting x, y, and b into y = mx + b. • Substitute m and b into y = mx + b (-8, 84), (5, -46) = -10 = m Pick point -46 = -10(5) + b Substitute in m and b y = -10x + 4 -46 = -50 + b +50 +50 4 = b