math problem
posted by Lavern on .
please help
Simplify
Multiply
(2ã74ã2)(5ã7+10ã2)

Assuming your garbled symbol means √, we have
(2√7  4√2)(5√7 + 10√2)
just think of these as polynomials in x and y
(2x4y)(5x+10y) = 10x^2  40y^2
letting x = √7 and y = √2, we have
10(√7)^2  40(√2)^2 = 10*740*2 = 10
Some work could have been saved by noting that
(2√7  4√2)(5√7 + 10√2)
= 2(√72√2) * 5(√7+√2)
= 10(√72√2)(√7+2√2)
= 10(78)