Bài 1: Hàm số <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>y</mi><mo>=</mo><mi>a</mi><msup><mi>x</mi><mn>2</mn></msup><mo>&#160;</mo><mfenced><mrow><mi>a</mi><mo>&#8800;</mo><mn>0</mn></mrow></mfenced></math>