Question

Solve the simultaneous equations 3x + 5y = 24
x + 7y = 56

Answer 1

ʜᴇʟʟᴏ ᴍᴀᴛᴇ!

3x + 5ʏ = 24 -------(1)

x + 7ʏ = 56 ----------(2)

ᴍᴜʟᴛɪᴘʟʏ - 3 ғʀᴏᴍ ᴇǫᴜᴀᴛɪᴏɴ (2)

ᴡᴇ ɢᴇᴛ

- 3x - 21ʏ = - 168 -------(3)

ᴀᴅᴅ (1) ᴀɴᴅ (3)

ᴡᴇ ɢᴇᴛ,

- 16ʏ = - 144
ʏ = 9

ᴋᴇᴇᴘɪɴɢ ᴠᴀʟᴜᴇ ᴏғ ʏ ɪɴ ᴇǫᴜᴀᴛɪᴏɴ (2) ᴡᴇ ɢᴇᴛ,

x + 7(9) = 56
x = 56 - 63
x = - 7
ʜᴇɴᴄᴇ x = - 7 ᴀɴᴅ ʏ = 9

ʜᴏᴘᴇ ɪᴛ ʜᴇʟᴘs

Answer 2

3x + 5y =56 $ x + 7y =56
Subtracting equation 1 from two we get
-2x + 2y = 0
X = y
Now by substituting x with y we get in equation 2
X + 7y = 56
y + 7y = 56
y = 7
x = 7