Use these 2 simultaneous equations to find x & y: 5y+21=9x and 6x+7y=45
Okay so first, to make the process more simple, I would suggest collecting all algebraic terms on the same side of the question as to get: 9x-5y=21 and 7y+6x=45 (as it already is). Next, looking at both equations, pick either the x or y coefficient and find the lowest common multiple of them i.e. the lowest common multiple of 6 & 9 is 18 so we multiple the first equation by 2 to get 18x-10y=42 and the second equation by 3 to get 21y+18x=135. We do this so we can either add or subtract the equations to eliminate either x or y. In this case, we should take the first equation away from the second: 21y--10y=93 or 31y=93. This simplifies so y=3
Now, we can substitute y=3 into one of the original equations to find x. 5(3)+21=9x therefore 9x=36. Simplifying again, x=4. We can check this by substituting both found variables into the other equation: 6(4)+7(3)=45. As 24+21=45 is true, the answer must be correct.
Related Maths GCSE answers
All answers ▸A pen is the shape of an equilateral triangle. A goat is attached to a corner of the pen on a rope. The goat eats all the grass it can reach. It can just reach the opposite fence of the pen. What percentage of the grass in the pen does the goat eat?
simplfy x/3 + x/4
The straight line L1 passes through the points with coordinates (4, 6) and (12, 2) The straight line L2 passes through the origin and has gradient -3. The lines L1 and L2 intersect at point P. Find the coordinates of P.
How do you use the pythagoras equation?