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Algebraic Roots & Indices

Exam code: 4024
Written by: Ashika|Reviewed by: Caroline Carroll|Updated 2 July 2026

Algebraic Roots & Indicesvideo

Algebraic Roots & Indices

Algebraic roots & indices

What are the laws of indices?

  • Index laws are rules you can use when doing operations with powers

    • They work with both numbers and algebra

Law

Description

How it works

a1=a{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

Anything to the power of 1 is itself

x1=x{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

a0=1{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

Anything to the power of 0 is 1

b0=1{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

am×an=am+n{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

To multiply indices with the same base, add their powers

c3×c2=c×c×c×c×c=c5{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

am÷an=aman=am-n{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

To divide indices with the same base, subtract their powers

d5÷d2=d×d×d×d×dd×d=d3 {"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

amn=amn{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

To raise indices to a new power, multiply their powers

e32=e×e×e×e×e×e=e6{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

abn=anbn{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

To raise a product to a power, apply the power to both numbers, and multiply

f×g2=f2×g2=f2g2{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

abn=anbn{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

To raise a fraction to a power, apply the power to both the numerator and denominator

hi2=h2i2{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

a-1=1a{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

a-n=1an{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

A negative power is the reciprocal

 j-1=1j{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

k-3=1k3{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

ab-n=ban=bnan{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""}

A fraction to a negative power, is the reciprocal of the fraction, to the positive power

lm-3=ml3=m3l3{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""}

a1n=an{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""}

The fractional power 1n{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""} is the nth root ( n-th root of blank)

n12=n2{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""}

p13=p3{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""}

a-1n=1a1n=1an{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""}

A negative, fractional power is one over a root

q-12=1q2{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""}

r-13=1r3{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""}

amn=a1n×m=a1nm=anm=am1n=amn{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""}

The fractional power mn{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""} is the nth root all to the power m, open parentheses n-th root of blank close parentheses to the power of m, or the nth root of the power m, n-th root of open parentheses blank close parentheses to the power of m end root (both are the same)

s23=s132=s32{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""}

s23=s213=s23{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""}

  • These can be used to simplify expressions 

    • Work out the number and algebra parts separately

      • 3x7×6x4=3×6×x7×x4=18x7+4=18x11{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

      • 6x73x4=63×x7x4=2x7-4=2x3 {"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

      • 3x72=32×x72=9x14{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

How do I find an unknown inside a power?

  • A term may have a power involving an unknown

    • E.g. 74x{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""}

  • If both sides of an equation have the same base number, then the powers must be equal

    • E.g. If 43x=49{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""} then 3x=9{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""}

    • And x=3{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""}

  • You may have to do some simplifying first to reach this point

    • E.g. 32x×34=318{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""} simplifies to 32x+4=318{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""}

    • Therefore 2x+4=18{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""}

    • And x=7{"fontFamily":"Times New Roman","fontSize":"18","autoformat":true,"toolbar":""}