Evaluate the variable expression when x = – 4

– 10x²

${\text{a}}^{\text{x}}\to$a is the base and x is exponent.

The power is the result of repeated multiplication of the same factor.

The expressionsa^xthis means that a has been used as a factor x times

Example: Find the base and the exponent of 2⁷ and evaluate the value.

Rule: ${\text{a}}^{\text{x}}\to$a is called base and x is exponent.

a = 2 and x = 7

Base = 2 and exponent = 7

Evaluate: $2^7=2 · 2 · 2 · 2 · 2 · 2 · 2 =128$

Evaluate the expression – 10x² when x = – 4

According to the exponent rule:

${\text{a}}^{\text{x}}\to$a is called base and x is power.

a = x and x = 2

In repeated multiplication:$x^2 = x · x$

Rule:The product of three negative integers is negative.

When x = – 4:$10x^2 = - 10 · x · x = - 10 · x · x = - 10 · (- 4) · (- 4) = - 160$

The value of– 10x² after evaluating the power is – 160 when x = – 4.