First, we need to find out the length of the third side of the triangle. (The right side of the Y-axis) We use the pythagorean theorem to find it. 4²+2² = 20 find the square root of 20 √20 = ~4.5 so with this in mind, lets find the length of the whole triangle. 8²+4²=80 then √80 = ~9 with this, we can say that since the length of one of the legs has increased by 2, and so has the length of the base, and also the length of the hypotenuse, the scale factor must be 2.
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graphically? well, you graph them both, the solutions is where they both intersect each other, since there are two solutions, meaning they will meet twice, or namely the linear will run into the quadratic curve twice, and where they meet, those x,y coordinates are the solutions to the system.