Join 60,000+ competitive exam aspirants
Expand the expression (4x + 3y + 5z)2.
16x2+9y2+25z2+24xy+30yz+40xz
16x2+9y2+25z2+12xy+15yz+20xz
4x2+3y2+5z2+24xy+30yz+40xz
16x2+9y2+25z2+24xy+30yz+20xz
16x2+9y2+25z2+24xy+30yz+40xz
Verify the individual squared terms first to eliminate incorrect options, then check the cross-term coefficients.
The expression to expand is (4x+3y+5z)2.
(a+b+c)2=a2+b2+c2+2ab+2bc+2ca
Verify the individual squared terms first to eliminate incorrect options, then check the cross-term coefficients.
Forgetting to multiply the cross-terms by the factor of 2.
Identify Formula
Use the standard algebraic identity for the square of a trinomial: (a+b+c)2=a2+b2+c2+2ab+2bc+2ca.
(a+b+c)2=a2+b2+c2+2ab+2bc+2ca
Substitute Values
Substitute a=4x, b=3y, and c=5z into the identity.
(4x+3y+5z)2=(4x)2+(3y)2+(5z)2+2(4x)(3y)+2(3y)(5z)+2(5z)(4x)
Simplify Terms
Calculate each term individually to get the final expanded polynomial expression.
16x2+9y2+25z2+24xy+30yz+40xz
A is correct because expanding the expression yields 16x2+9y2+25z2+24xy+30yz+40xz.
Mastering algebraic expansion identities saves valuable time in RRB and other competitive quantitative aptitude tests.