How do i solve two linear simultaneous equations 2x+y=7 & 3x-y=8 ?
To start with, try and spot whether or not two of the coeffecients (numbers next to the letters) are the same for either question (i.e. could be a 3x in one equation and a 3x in the other). This also works if the number is the same but the sign is different (i.e. 2x and -2x). As one equation contains a y, and the other contains a -y, you need to add the two equations together to eliminate the y, leaving 5x=15.
Dividing through by 5 leaves x=3, and if you substitute this back into either of the original equations you get that y=1.
TB
Related Maths A Level answers
All answers ▸How do you intergrate sin^2(x)?
Two fair six sided dice, called A and B, are rolled and the results are added together. The sum of the dice is 8, what is the probability that two fours were rolled?
(A) express 4^x in terms of y given that 2^x = y. (B) solve 8(4^x ) – 9(2^x ) + 1 = 0
The quadratic equation (k+1)x^2+12x+(k-4)=0 has real roots. (a) Show that k^2-3k-40<=0. (b) Hence find the possible values of k.