Big Ideas Math Integrated I, 2016
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Big Ideas Math Integrated I, 2016 View details
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Exercise 5 Page 267

If either of the variable terms would cancel out the corresponding variable term in the other equation, you can use the Elimination Method to solve the system.

No solution, see solution.

Practice makes perfect
Since neither equation has a variable with a coefficient of 1 to use the Substitution Method, we will use the Elimination Method. To solve a system of linear equations using the Elimination Method, one of the variable terms needs to be eliminated when one equation is added to or subtracted from the other equation. This means that either the x-terms or the y-terms must cancel each other out. 6 x-4 y=9 & (I) 9 x-6 y=15 & (II) Currently, none of the terms in this system will cancel out. Therefore, we need to find a common multiple between two variable like terms in the system. If we multiply Equation (I) by 3 and multiply Equation (II) by -2, the x-terms will have opposite coefficients. 3(6 x-4 y)=3(9) -2(9 x-6 y)=-2(15) ⇓ 18x-12 y=27 -18x+12 y=-30 We can see that the x-terms and the y-terms will eliminate each other if we add Equation (I) to Equation (II).
18x-12y=27 -18x+12y=-30
18x-12y=27 -18x+12y+( 18x-12y)=-30+( 27)
18x-12y=27 0=-3 *
Solving this system of equations resulted in a contradiction; 0 can never be equal to -3. Therefore, the lines are parallel and do not have a point of intersection.