Question

Daca a-b=5 si a²-b2=420, aflati valoarea sumei a+b

Answer 1

a²-b²=(a-b)(a+b)

420=5(a+b)

a+b=420:5

a+b=84

Answer 2

a² - b² = (a-b)(a+b)

a - b = 5

420 = 5 × (a+b)

a + b = $\frac{420}{5}$

a + b = 84