Behaviour being used: Adaptive mode
Minimum fraction: 0
Question summary: [D e t e r m i n e space c u a l space o space c u a l e s space d e space l a s space s i g u i e n t e s space p r o p o s i c i o n e s space s o n space v e r d a d e r a s space p a r a t o d o space n space element of space straight natural numbers colon]: 1<mrow><mo>+</mo></mrow>2<mrow><mo>+</mo></mrow>4<mrow><mo>+</mo></mrow>...<mrow><mo>+</mo></mrow>2<mrow><sup><mi>n</mi></sup></mrow><mrow><mo>=</mo></mrow>2<mrow><sup><mi>n</mi></sup></mrow><mrow><mo>-</mo></mrow>1; 1 + 2 + 3 + ... + (n - 1) = ( ( ( n ) · ( ( ( ( n ) - ( 1 ) ) ) ) ) / ( 2 ) ); 1<mrow><mo>+</mo></mrow>3<mrow><mo>+</mo></mrow>5<mrow><mo>+</mo></mrow>...<mrow><mo>+</mo></mrow>(2n<mrow><mo>-</mo></mrow>1)<mrow><mo>=</mo></mrow>n<mrow><sup><mn>2</mn></sup></mrow>
Right answer summary: 1 + 2 + 3 + ... + (n - 1) = ( ( ( n ) · ( ( ( ( n ) - ( 1 ) ) ) ) ) / ( 2 ) )
Question state: todo