Question

Without actually calculating the cubes , find the value of (-1) 3 +(-2) 3 +(-3) 3 + (-4) 3 +2(5) 3 Also write the identity used

Answer 1

identity:1^3+2^3+3^3+4^3+............................n^3={n(n+1)/2}^2
where is no of terms.
here in acc. to ques,
(-1) 3 +(-2) 3 +(-3) 3 + (-4) 3 = -((1) ^3 +(2) ^3 +(3)^ 3 + (4) ^3)
{because -1^3=-1}
= -{4(4+1)/2}^2
= -100
(-1) 3 +(-2) 3 +(-3) 3 + (-4) 3 +2(5) 3 = -100+2*125= -100+250=150

Answer 2

Hope you understand !!

Please mark me down as BRAINIEST