Substitute y from the second equation in the first equation: x^2+(2x+3)^2=24, so x^2+4x^2+12x-15=0.
5x^2+12x-15=0. Solve using the formula: x=(-12+sqrt(144+300))/10=0.9071 or -3.3071.
Therefore y=2x+3=4.8143 or -3.6143.
Check: 0.9071^2+4.8143^=24; 4.8143=2*0.9071+3;
(-3.3071)^2+(-3.6143)^2=24; -3.6143=2*(-3.3071)+3.
Two solutions: (0.9071,4.8143) and (-3.3071,-3.6143).