Question

Calculati folosind factorul comun a) 2^3+2^4+2^5=. b)3^6+3^5-11•3^4=. c) 5^5+5^4-20•5^3=

Answer 1

a)  2³ + 2⁴ + 2⁵ = 2³ ( 1 + 2 + 2²) = 8 ×( 3 + 4 ) = 8 × 7 = 56 

b) 3⁶ + 3⁵ - 11 ˣ 3⁴ = 3⁴ ( 3² + 3 - 11) = 81 ˣ ( 9 + 3 - 11) = 81 ˣ( 12 - 11) = 81

c) 5⁵ + 5⁴ - 20 ˣ 5³ = 5⁵ + 5⁴ - 4 ˣ 5 ˣ 5³ = 1 250

= 5⁵ + 5⁴ - 5⁴ ˣ 4 =

= 5⁴ ( 5 + 1 - 4) =

= 5⁴ ˣ 2 = 

= 625 ˣ 2 = 

= 1 250