Question

2√7+3√7-√28; 2√18+5√2-√72; √5(1/√5-2/√5); -√8(2/12+2√2);

Answer 1

2√7+3√7-√28=2√7+3√7-2√7=3√7
2√18+5√2-√72=2×3√2+5√2-6√2=6√2+5√2-6√2=5√2
√5(1/√5-2/√5)=√5(√5/5-2√5/5)=√5×(-√5/5)=-√25/5=-5/5=-1
-√8(2/12+2√2)=-2√2[(2+24√2)/12]=-2√2[2(1+12√2)/12]=-2√2(1+12√2)/6=(-2√2-24√4)/6
=(-2√2-24×2)/6=(-2√2-48)/6=2(-√2-24)/6=(-√2-24)/3