How do you simplify #y = (x - 1)(5x + 2)#?

1 Answer
Jun 20, 2016

Answer:

#y=5x^2-3x-2#

Explanation:

Multiply everything in one bracket by everything inside the other. WHATCH THE SIGNS!
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#color(blue)("Method example using numbers")#

Consider #6xx3=18#
But 6 can be 'split' (partitioned) into 4 + 2 so we have

#(4+2)xx3=18# The values have not changed, just the way they look.

Write as #3(4+2)#

So this is 3 lots of #(4+2)#

#->" "(4+2)+(4+2)+(4+2)#

#=4+4+4" "+2+2+2#

#=3xx4" "+" "3xx2" " =" " 12+6" "=" "18#

So we have multiplied everything inside the bracket by 3

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Given:#" "color(blue)((x-1)color(brown)((5x+2))#

#color(brown)(color(blue)(x)(5x+2)color(blue)(-1)(5x+2) )#

#5x^2+2x" "-5x-2#

#5x^2-3x-2#

#color(magenta)("Take it one step at a time ")#

and watch those signs