Question

4/2+v2-5+2v2=

explicati va rog frumos ..

Answer 1

4/(2+√2)-5+2√2=[4(2-√2)]/[(2+√2)(2-√2)]-5+2√2=
=[4(2-√2)]/(4-2)-5+2√2=[4(2-√2)]/2-5+2√2=
=4/2*(2-√2)-5+2√2=2(2-√2)-5+2√2=
=4-2√2-5+2√2=4-5-2√2+2√2=-1

Answer 2

[tex]\dfrac{4}{2+\sqrt2}-5+2\sqrt2=\dfrac{4(2-\sqrt2)}{4-2}-5+2\sqrt2=\dfrac{4(2-\sqrt2)}{2}-5+2\sqrt2 =\\\;\\ = 2(2-\sqrt2)-5+2\sqrt2 =4-2\sqrt2-5+2\sqrt2= 4-5=-1.[/tex]