Answer:
(10 - 7x)²
Step-by-step explanation:
Note that this expression is a perfect square of the form
(a - bx)² = a² - 2abx + b²x²
Compare 100 - 140x + 49x² to the above
a² = 100 ⇒ a = [tex]\sqrt{100}[/tex] = 10
b² = 49 ⇒ b = [tex]\sqrt{49}[/tex] = 7
and - 2ab = - 2 × 10 × 7 = - 140, thus
100 - 140x + 49x² = (10 - 7x)² ← in factored form
