Question

If xy = 20 and (x + y)^2= 70, then x^2+ y^2 is equal to

Answer 1

Answer:

30

Step-by-step explanation:

$(x+y)^{2} =70\\x^{2} + y^{2} + 2xy =70\\x^{2} + y^{2} + 2(20)=70\\x^2 + y^2 + 40=70\\x^2 + y^2 = 70 - 40\\x^2 + y^2 = 30$

Answer 2

Answer:

30

Step-by-step explanation:

(x+y)^2 =70

x^2 +2xy+y^2 =70 [ a+b)^2 = a^2 +2ab+ b^2 ]

x^2 + 2(20) + y^2 =70 [ given xy= 20]

x^2 + 40+ y^2 = 70

x^2 + y^2 =70-40

x^2 + y^2 =30