Solve these simultaneous equations.....3a+2b = 17 and 8a-2b= 60

3a+2b = 178a-2b = 60We are going to solve this using the elimination method. This means that we are going to eliminate the variable (or letter) that has the same value in each equation. In this case it is the 'b' because both equations have '2b' in them. Using the SSS abbreviation, which stands for Same Sign Subtract, we can see that the '2b' actually has different signs in the two equations; in the top one it is positive, and in the bottom one it is a negative.With different signs, we therefore have to add the two equations, and this in turn will eliminate the 'b' variable. So if we add 8a+3a we get 11a, and if we get 60 + 17 we get 77. Lining up the variables and the equals sign we get 11a=77. Dividing both sides by 11 gives you a=7. You can then pick either equation to substitute this value back into. Taking the top equation; 3a+2b = 17, we can say 3(7) + 2b =17. Therefore 21 + 2b = 17. Subtracting 21 from both sides gives 2b=-4 and therefore b= -2. Those are your two answers

JO
Answered by Joel O. Maths tutor

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