Question

Dado a -2b=5,calcule o valor numérico da expressão :
A=5a²-20ab+20b²

pf respondam

Answer 1

Olá Beatriz!!

$\\ \mathsf{A = 5a^2 - 20ab + 20b^2} \\\\ \mathsf{A = 5(a^2 - 4ab + 4b^2)} \\\\ \mathsf{A = 5(\underbrace{a - 2b}_{5})^2} \\\\ \mathsf{A = 5 \cdot (5^2)} \\\\ \boxed{\mathsf{A = 125}}$